Author: "Department of Chemistry [Berkeley]" / Language: english - Searchworks@Jio Institute Digital Library Search Results

Your search keyword '"Department of Chemistry [Berkeley]"' showing total 83 results

Start Over Author "Department of Chemistry [Berkeley]" Language english

83 results on '"Department of Chemistry [Berkeley]"'

1. Metallacyclic actinide catalysts for dinitrogen conversion to ammonia and secondary amines

Author: Rory P. Kelly, Tatsumi Ochiai, Megan L. Seymour, Laurent Maron, Polly L. Arnold, Francis Y. T. Lam, EPCC [Edinburgh], University of Edinburgh, Université de Tsukuba = University of Tsukuba, Department of Chemistry [Berkeley], University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), EaStCHEM School of Chemistry, University of St Andrews [Scotland], Nanomagnétisme (LPCNO), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Silanes, 010405 organic chemistry, General Chemical Engineering, Organic Chemistry, General Chemistry, Actinide, 010402 general chemistry, Ligands, 01 natural sciences, 0104 chemical sciences, Catalysis, Metal, Ammonia, chemistry.chemical_compound, Temperature and pressure, chemistry, visual_art, Polymer chemistry, Chemical Sciences, visual_art.visual_art_medium, Surface modification, Molecule, MESH: chemi, [CHIM]Chemical Sciences, Chemical bonding
Abstract: International audience; Chemists have spent over a hundred years trying to make ambient temperature/pressure catalytic systems that can convert atmospheric dinitrogen into ammonia or directly into amines. A handful of successful d-block metal catalysts have been developed in recent years, but even binding of dinitrogen to an f-block metal cation is extremely rare. Here we report f-block complexes that can catalyse the reduction and functionalization of molecular dinitrogen, including the catalytic conversion of molecular dinitrogen to a secondary silylamine. Simple bridging ligands assemble two actinide metal cations into narrow dinuclear metallacycles that can trap the diatom while electrons from an externally bound group 1 metal, and protons or silanes, are added, enabling dinitrogen to be functionalized with modest but catalytic yields of six equivalents of secondary silylamine per molecule at ambient temperature and pressure.
Published: 2020
Full Text: View/download PDF

2. Regiospecificity in Ligand-Free Pd-Catalyzed C–H Arylation of Indoles: LiHMDS as Base and Transient Directing Group

Author: Clément Camp, Marc Renom-Carrasco, Florian M. Wisser, Chloé Thieuleux, Jérôme Canivet, Yorck Mohr, Clément Demarcy, Eric Clot, Elsje Alessandra Quadrelli, Laboratoire de Chimie, Catalyse, Polymères et Procédés, R 5265 (C2P2), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, IRCELYON-Ingéniérie, du matériau au réacteur (ING), Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)
Subjects: Indole test, chemistry.chemical_classification, Base (chemistry), Lithium hexamethyldisilazide, 010405 organic chemistry, Ligand, C-H arylation, chemistry.chemical_element, General Chemistry, LiHMDS, 010402 general chemistry, palladium, 01 natural sciences, Medicinal chemistry, Catalysis, 0104 chemical sciences, chemistry, indole, cross-coupling, [CHIM]Chemical Sciences, Palladium
Abstract: International audience; A highly efficient catalyst-base pair for the C-H arylation of free (NH)-indoles in the C-3 position is reported. Ligand-free palladium acetate coupled with lithium hexamethyldisilazide (LiHMDS) catalyzed the regiospecific, i.e. 100% regioselective, C-3 arylation of indoles with high turnover numbers. This catalytic system has been successfully applied to a wide range of substrates including various functional aryl halides and indolic cores. The unique role of LiHMDS as both a base and unexpected transient directing group has been revealed experimentally and elucidated computationally, in line with a Heck-type insertion-elimination mechanism.
Published: 2020
Full Text: View/download PDF

3. Metallacyclic actinide catalysts for dinitrogen conversion to ammonia and secondary amines (vol 15, pg 312, 2020)

Author: Arnold, Polly L., Ochiai, Tatsumi, Lam, Francis Y. T., Kelly, Rory P., Seymour, Megan L., Maron, Laurent, Department of Chemistry [Berkeley], University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), University of Edinburgh, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph]
Published: 2020
Full Text: View/download PDF

4. Field-dependent ionic conductivities from generalized fluctuation-dissipation relations

Author: Chloe Ya Gao, Dominika Lesnicki, Benjamin Rotenberg, David T. Limmer, PHysicochimie des Electrolytes et Nanosystèmes InterfaciauX (PHENIX), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Liquides Ioniques et Interfaces Chargées (LI2C), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Lawrence Berkeley National Laboratory [Berkeley] (LBNL)
Subjects: General Physics, Materials science, FOS: Physical sciences, General Physics and Astronomy, Ionic bonding, Thermodynamics, Non-equilibrium thermodynamics, Molecular dynamics, Conductivity, 01 natural sciences, Mathematical Sciences, Engineering, Electric field, 0103 physical sciences, Electrical conductivity, Ionic conductivity, 010306 general physics, Condensed Matter - Statistical Mechanics, [PHYS]Physics [physics], Statistical Mechanics (cond-mat.stat-mech), Nonequilibrium fluctuations, Strong electrolyte, Condensed Matter::Soft Condensed Matter, Ionic strength, Physical Sciences, Nonequilibrium systems
Abstract: We derive a relationship for the electric field dependent ionic conductivity in terms of fluctuations of time integrated microscopic variables. We demonstrate this formalism with molecular dynamics simulations of solutions of differing ionic strength with implicit solvent conditions and molten salts. These calculations are aided by a novel nonequilibrium statistical reweighting scheme that allows for the conductivity to be computed as a continuous function of the applied field. In strong electrolytes, we find the fluctuations of the ionic current are Gaussian and subsequently the conductivity is constant with applied field. In weaker electrolytes and molten salts, we find the fluctuations of the ionic current are strongly non-Gaussian and the conductivity increases with applied field. This nonlinear behavior, known phenomenologically for dilute electrolytes as the Onsager-Wien effect, is general and results from the suppression of ionic correlations at large applied fields, as we elucidate through both dynamic and static correlations within nonequilibrium steady-states., 6 pages, 3 figures
Published: 2019
Full Text: View/download PDF

5. Envisioning the next decade of Galactic Center science: a laboratory for the study of the physics and astrophysics of supermassive black holes

Author: Do, Tuan, Ghez, Andrea, Lu, Jessica R., Morris, Mark, Hosek Jr., Matthew, Hees, Aurelien, Naoz, Smadar, Ciurlo, Anna, Armitage, Philip J., Beaton, Rachael L, Becklin, Eric, Bellini, Andrea, Bentley, Rory O., Bland-Hawthorn, Joss, Chakrabarti, Sukanya, Chen, Zhuo, Chu, Devin S., Dehghanfar, Arezu, Gammie, Charles F., Gautam, Abhimat K., Genzel, Reinhard, Greene, Jenny, Haggard, Daryl, Hora, Joseph, Kerzendorf, Wolfgang E., Libralato, Mattia, Nishiyama, Shogo, O'Neil, Kelly Kosmo, Ozel, Feryal, Paumard, Thibaut, Perets, Hagai B., Psaltis, Dimitrios, Quataert, Eliot, Ramirez-Ruiz, Enrico, Rich, R Michael, Rasio, Fred, Sakai, Shoko, Schoedel, Rainer, Smith, Howard, Weinberg, Nevin N., Witzel, Gunther, Department of Physics and Astronomy [UCLA, Los Angeles], University of California [Los Angeles] (UCLA), University of California-University of California, Department of Chemistry [Berkeley], University of California [Berkeley], Systèmes de Référence Temps Espace (SYRTE), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Observatoire de Paris - Site de Meudon (OBSPM), Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Centre National de la Recherche Scientifique (CNRS), Anglo-Australian Observatory (AAO), Shandong Provincial Key Laboratory of Plant Stress, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and UCLA
Subjects: Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Astrophysics::Galaxy Astrophysics
Abstract: 9 pages, 4 figures, submitted for Astro2020 White Paper; As the closest example of a galactic nucleus, the Galactic center (GC) presents an exquisite laboratory for learning about supermassive black holes (SMBH) and their environment. We describe several exciting new research directions that, over the next 10 years, hold the potential to answer some of the biggest scientific questions raised in recent decades: Is General Relativity (GR) the correct description for supermassive black holes? What is the nature of star formation in extreme environments? How do stars and compact objects dynamically interact with the supermassive black hole? What physical processes drive gas accretion in low-luminosity black holes? We describe how the high sensitivity, angular resolution, and astrometric precision offered by the next generation of large ground-based telescopes with adaptive optics will help us answer these questions. First, it will be possible to obtain precision measurements of stellar orbits in the Galaxy's central potential, providing both tests of GR in the unexplored regime near a SMBH and measurements of the extended dark matter distribution that is predicted to exist at the GC. Second, we will probe stellar populations at the GC to significantly lower masses than are possible today, down to brown dwarfs. Their structure and dynamics will provide an unprecedented view of the stellar cusp around the SMBH and will distinguish between models of star formation in this extreme environment. This increase in depth will also allow us to measure the currently unknown population of compact remnants at the GC by observing their effects on luminous sources. Third, uncertainties on the mass of and distance to the SMBH can be improved by a factor of $\sim$10. Finally, we can also study the near-infrared accretion onto the black hole at unprecedented sensitivity and time resolution, which can reveal the underlying physics of black hole accretion.
Published: 2019

6. A Uranium Tri-Rhenium Triple Inverse Sandwich Compound

Author: John Arnold, Trevor D. Lohrey, Guodong Rao, Laurent Maron, Michael A. Boreen, R. David Britt, Department of Chemistry [Berkeley], University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences Heavy Element Chemistry Program of the U.S. Department of Energy (DOE) at LBNL [DE-AC02-05CH11231], National Science Foundation Graduate Research Fellowship Program [DGE 1106400], U.S. DOE Integrated University Program, National Institutes of Health [1R35GM126961-01], Chinese Academy of Science, Humboldt Foundation, and Office of Science, Office of Basic Energy Sciences, of the U.S. DOE [DE-AC02-05CH11231]
Subjects: Models, Molecular, Molecular Conformation, chemistry.chemical_element, Salt (chemistry), Crystallography, X-Ray, 010402 general chemistry, Metathesis, 01 natural sciences, Biochemistry, Catalysis, Adduct, law.invention, chemistry.chemical_compound, Colloid and Surface Chemistry, law, Organometallic Compounds, Lewis acids and bases, Electron paramagnetic resonance, chemistry.chemical_classification, General Chemistry, Rhenium, Uranium, 0104 chemical sciences, Crystallography, chemistry, Sandwich compound, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph]
Abstract: International audience; Salt metathesis between the anionic rhenium(I) compound, Na[Re(eta(5)-Cp)(BDI)] (BDI = N,N'-bis(2,6-diisopropylphenyl)-3,5-dimethyl-beta-diketiminate), and the uranium(III) salt, UI3 (1,4-dioxane)(1.5), generated the triple inverse sandwich complex, U[(mu-eta(5):eta(5)-Cp)Re(BDI)(3), which was isolated and structurally characterized as the Lewis base adducts, (L)U[(mu-eta(5):eta(5)-Cp)Re(BDI)](3) (1.L, L = THF, 1,4-dioxane, DMAP). The assignment as one uranium(III) and three rhenium(I) centers was supported by X-ray crystallography, NMR and EPR spectroscopies, and computational studies. An unusual shortening of the rhenium-Cp bond distances in 1.L relative to Na[Re(eta(5)-Cp)(BDI)] was observed in the solid-state and reproduced in calculated structures of 1-THF and the anionic fragment, [Re(eta(5)-Cp)(BDI)](-). Calculations suggest that the electropositive uranium center pulls electron density away from the electron-rich rhenium centers, reducing electron-electron repulsions in the rhenium-Cp moieties and thereby strengthening those interactions, while also making uranium-Cp bonding more favorable.
Published: 2019
Full Text: View/download PDF

7. A linear cobalt(II) complex with maximal orbital angular momentum from a non-Aufbau ground state

Author: Jacob Overgaard, Emil Damgaard-Møller, I. Crassee, Joris van Slageren, Mauro Perfetti, Frank Neese, Philip C. Bunting, Mihail Atanasov, Jeffrey R. Long, Milan Orlita, Max Planck Institute for Chemical Energy Conversion, Max-Planck-Gesellschaft, Institut für Physikalische Chemie, Universität Stuttgart [Stuttgart], Laboratoire national des champs magnétiques intenses - Grenoble (LNCMI-G ), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre for Materials Crystallography, Aarhus University [Aarhus], Physikalisches Institut [Stuttgart] (Pfaffenwaldring 57, D–70550 Stuttgart, Germany), Max-Planck-Institut für Chemische Energiekonversion (MPI-CEC), University of California [Berkeley], University of California, Laboratoire des champs magnétiques intenses (LCMI-GHMFL), Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [Berkeley], and University of California-University of California
Subjects: Physics, Ligand field theory, Angular momentum, Multidisciplinary, 010405 organic chemistry, Magnetism, 010402 general chemistry, 01 natural sciences, Molecular physics, Magnetic susceptibility, 0104 chemical sciences, Magnetic anisotropy, Atomic orbital, [CHIM]Chemical Sciences, Electron configuration, Ground state, ComputingMilieux_MISCELLANEOUS
Abstract: INTRODUCTION The magnetic properties of a single metal center are determined by a combination of its total spin S and orbital angular momentum L . Orbital angular momentum gives rise to magnetic anisotropy, an essential property for applications such as information storage and high-coercivity magnets. Unquenched L arises from an odd number of electrons in degenerate orbitals and is typically observed only for free ions, as well as for complexes of the f elements. For the majority of transition metal ions, however, orbital angular momentum is quenched by the ligand field, which removes the requisite orbital degeneracies. Maximal L for a transition metal ( L = 3) would require an odd number of electrons in two sets of degenerate orbitals. Such a species would entail a non-Aufbau configuration, wherein the electrons do not fill the d orbitals in the usual order of lowest to highest in energy, and likely exhibit a large magnetic anisotropy. RATIONALE Previous efforts have identified the utility of linear coordination environments for isolating iron complexes with unquenched orbital angular momentum and large magnetic anisotropies. Crucially, transition metals in this environment are unaffected by Jahn-Teller distortions that would otherwise remove orbital degeneracies in the case of partially filled d orbitals. Separately, cobalt atoms deposited on a MgO surface—for which one-coordination of the metal is achieved, provided a vacuum is maintained—were shown to have L = 3, giving rise to near-maximal magnetic anisotropy. Calculations on the hypothetical linear molecule Co(C(SiMe 3 ) 3 ) 2 (where Me is methyl) also predicted that this system would possess a ground state with L = 3. Empirically, maximal L in a transition metal complex thus requires both a linear coordination environment and a sufficiently weak ligand field strength to allow for non-Aufbau electron filling. RESULTS The strongly reducing nature of the carbanion ligand hinders isolation of dialkyl cobalt(II) complexes. However, reducing the basicity of the central carbanion through the use of electron-withdrawing aryloxide groups allowed for the synthesis of the dialkyl cobalt(II) complex Co(C(SiMe 2 ONaph) 3 ) 2 , where Naph is a naphthyl group. Ab initio calculations on this complex predict a ground state with S = 3 / 2 , L = 3, and J = 9 / 2 arising from the non-Aufbau electron configuration (d x 2 –y 2 , d xy ) 3 (d xz , d yz ) 3 (d z 2 ) 1 . Much as for lanthanide complexes, the ligand field is sufficiently weak that interelectron repulsion and spin-orbit coupling play the key roles in determining the electronic ground state. dc magnetic susceptibility measurements reveal a well-isolated M J = ± 9 / 2 ground state, and simulations of the magnetic data from the calculations are in good agreement with the experimental data. Variable-field far-infrared (FIR) spectroscopy shows a magnetically active excited state at 450 cm −1 that, in combination with calculations and variable-temperature ac magnetic susceptibility experiments, is assigned to the M J = ± 7 / 2 state. Modeling of experimental charge density maps also suggests a d-orbital filling with equally occupied (d x 2 –y 2 , d xy ), and (d xz , d yz ) orbital sets. As a consequence of its large orbital angular momentum, the molecule exhibits slow magnetic relaxation and, in a magnetically dilute sample, a coercive field of 600 Oe at 1.8 K. CONCLUSION Isolation of Co(C(SiMe 2 ONaph) 3 ) 2 illustrates how an extreme coordination environment can confer an f-element–like electronic structure on a transition metal complex. The non-Aufbau ground state enables realization of maximal orbital angular momentum and magnetic anisotropy near the physical limit for a 3d metal. In this respect, the linear L–Co–L motif may prove useful in the design of new materials with high magnetic coercivity.
Published: 2018
Full Text: View/download PDF

8. Reusable Enzymatic Fiber Mats for Neurotoxin Remediation in Water

Author: DelRe, Christopher, Huang, Charley, Li, Tim, Dennis, Patrick, Drockenmuller, Eric, Xu, Ting, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Ingénierie des Matériaux Polymères (IMP), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet [Saint-Étienne] (UJM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Univ Calif Berkeley, Dept Mat Sci & Engn
Subjects: [CHIM.POLY]Chemical Sciences/Polymers, [CHIM.MATE]Chemical Sciences/Material chemistry, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2018

9. Formation of the layered conductive magnet CrCl2(pyrazine)2 through redox-active coordination chemistry

Author: Jeffrey R. Long, Andrei Rogalev, Sebastian E. Reyes-Lillo, Jeffrey B. Neaton, Laura Voigt, Mathieu Rouzières, Michael L. Aubrey, Kasper S. Pedersen, Rodolphe Clérac, Zhongshan Li, Fabrice Wilhelm, Panagiota S. Perlepe, Daniel N. Woodruff, Dumitru Samohvalov, Anders Reinholdt, Kasper A. Borup, Technical University of Denmark [Lyngby] (DTU), Centre de Recherche Paul Pascal (CRPP), Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Department of Chemistry, University of Oxford, Molecular Fondry [LBNL Berkeley], Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Department of Physics [Berkeley], Departamento de Ciencias Fisicas, Universidad Andres Bello, Department of Chemistry [Copenhagen], Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Department of Chemistry, Technical University of Denmark, Lyngby, Centre for Storage Ring Facilities [Aarhus] (ISA), Aarhus University [Aarhus], Center for Materials Crystallography (CMC), Interdisciplinary Nanoscience Center (iNANO), European Synchrotron Radiation Facility (ESRF), University of California, Kavli Energy Nanosciences Institute at Berkeley, Department of Chemical & Biomolecular Engineering [Berkeley] (CBE), Materials Science Division [LBNL Berkeley], Departamento de Ciencias Fisicas [Santiago de Chile], and Universidad Andrés Bello [Santiago] (UNAB)
Subjects: Pyrazine, General Chemical Engineering, 02 engineering and technology, Conductivity, 010402 general chemistry, 01 natural sciences, law.invention, Coordination complex, chemistry.chemical_compound, Paramagnetism, Ferrimagnetism, law, chemistry.chemical_classification, Spintronics, Graphene, Ligand, Organic Chemistry, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, 3. Good health, 0104 chemical sciences, chemistry, Chemical physics, Chemical Sciences, 0210 nano-technology
Abstract: The unique properties of graphene, transition-metal dichalcogenides and other two-dimensional (2D) materials have boosted interest in layered coordination solids. In particular, 2D materials that behave as both conductors and magnets could find applications in quantum magnetoelectronics and spintronics. Here, we report the synthesis of CrCl2(pyrazine)2, an air-stable layered solid, by reaction of CrCl2 with pyrazine (pyz). This compound displays a ferrimagnetic order below ∼55 K, reflecting the presence of strong magnetic interactions. Electrical conductivity measurements demonstrate that CrCl2(pyz)2 reaches a conductivity of 32 mS cm–1 at room temperature, which operates through a 2D hopping-based transport mechanism. These properties are induced by the redox-activity of the pyrazine ligand, which leads to a smearing of the Cr 3d and pyrazine π states. We suggest that the combination of redox-active ligands and reducing paramagnetic metal ions represents a general approach towards tuneable 2D materials that consist of charge-neutral layers and exhibit both long-range magnetic order and high electronic conductivity.
Published: 2018
Full Text: View/download PDF

10. Off-axis point spread function characterization in laser guide star adaptive optics systems

Author: Etsuko Mieda, Jean-Pierre Véran, Carlos Correia, Olivier Beltramo-Martin, G. Witzel, Benoit Neichel, Jessica R. Lu, Thierry Fusco, Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Subaru Telescope, National Astronomical Observatory of Japan (NAOJ), DOTA, ONERA, Université Paris Saclay (COmUE) [Châtillon], ONERA-Université Paris Saclay (COmUE), Department of Physics and Astronomy [UCLA, Los Angeles], University of California [Los Angeles] (UCLA), University of California-University of California, Department of Chemistry [Berkeley], University of California [Berkeley], National Research Council (Victoria, Canada), University of California (UC)-University of California (UC), and University of California [Berkeley] (UC Berkeley)
Subjects: Point spread function, [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], instrumentation: adaptive optics, 01 natural sciences, methods: analytical, law.invention, Fraction of variance unexplained, 010309 optics, Photometry (optics), Telescope, Optics, law, 0103 physical sciences, Adaptive optics, 010303 astronomy & astrophysics, Physics, business.industry, Astronomy and Astrophysics, Astrometry, Laser, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], methods: data analysis, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Laser guide star, Space and Planetary Science, business, atmospheric effects
Abstract: Adaptive optics (AO) restore the angular resolution of ground-based telescopes, but at the cost of delivering a time- and space-varying point spread function (PSF) with a complex shape. PSF knowledge is crucial for breaking existing limits on the measured accuracy of photometry and astrometry in science observations. In this paper, we concentrate our analyses of the anisoplanatism signature only on to the PSF. For large-field observations (20 arcmin) with single-conjugated AO, PSFs are strongly elongated due to anisoplanatism that manifests itself as three different terms for laser guide star (LGS) systems: angular, focal and tilt anisoplanatism. First, we propose a generalized model that relies on a point-wise decomposition of the phase and encompasses the non-stationarity of LGS systems. We demonstrate that it is more accurate and less computationally demanding than existing models: it agrees with end-to-end physical-optics simulations to within 0.1 per cent of PSF measurables, such as the Strehl ratio, FWHM and the fraction of variance unexplained (FVU). Secondly, we study off-axis PSF modelling with respect to the C2n(h) Cn2(h) profile (heights and fractional weights). For 10-mclass telescopes, PSF morphology is estimated at the 1 per cent level as long as we model the atmosphere with at least seven layers, whose heights and weights are known with precisions of 200 m and 10 per cent, respectively. As a verification test, we used the Canada’s National Research Council – Herzberg NFIRAOS Optical Simulator (HeNOS) testbed data, featuring four lasers. We highlight the capability of retrieving off-axis PSF characteristics within 10 per cent of the FVU, which complies with the expected range from the sensitivity analysis. Our new off-axis PSF modelling method lays the groundwork for testing on-sky in the near future.
Published: 2018
Full Text: View/download PDF

11. NMR chemical shift analysis decodes olefin oligo- and polymerization activity of d0 group 4 metal complexes

Author: Satoru Shirase, Keishi Yamamoto, Christopher P. Gordon, Richard A. Andersen, Christophe Copéret, Odile Eisenstein, Department of Chemistry and Applied Biosciences [ETH Zürich] (D-CHAB), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), and Laboratory of Inorganic Chemistry
Subjects: chemistry.chemical_classification, Agostic interaction, Olefin fiber, Multidisciplinary, 010405 organic chemistry, Chemical shift, Nuclear magnetic resonance spectroscopy, Carbon-13 NMR, 010402 general chemistry, 01 natural sciences, Olefin polymerization, olefin oligomerization, NMR Spectroscopy, chemical shift tensor analysis, frontier molecular orbitals, 0104 chemical sciences, Crystallography, chemistry, Polymerization, PNAS Plus, [CHIM]Chemical Sciences, Molecular orbital, Alkyl, ComputingMilieux_MISCELLANEOUS
Abstract: d0 metal-alkyl complexes (M = Ti, Zr, and Hf) show specific activity and selectivity in olefin polymerization and oligomerization depending on their ligand set and charge. Here, we show by a combined experimental and computational study that the 13C NMR chemical shift tensors of the α-carbon of metal alkyls that undergo olefin insertion signal the presence of partial alkylidene character in the metal–carbon bond, which facilitates this reaction. The alkylidene character is traced back to the π-donating interaction of a filled orbital on the alkyl group with an empty low-lying metal d-orbital of appropriate symmetry. This molecular orbital picture establishes a connection between olefin insertion into a metal-alkyl bond and olefin metathesis and a close link between the Cossee–Arlmann and Green–Rooney polymerization mechanisms. The 13C NMR chemical shifts, the α-H agostic interaction, and the low activation barrier of ethylene insertion are, therefore, the results of the same orbital interactions, thus establishing chemical shift tensors as a descriptor for olefin insertion.
Published: 2018
Full Text: View/download PDF

12. Biporous Metal-Organic Framework with Tunable CO2/CH4 Separation Performance Facilitated by Intrinsic Flexibility

Author: Berend Smit, Jorge A. R. Navarro, Daniele Ongari, Peter G. Boyd, Iurii Dovgaliuk, Kathryn S. Deeg, Kaili Y. Ordiz, Arunraj Chidambaram, Seyed Mohamad Moosavi, Kyriakos C. Stylianou, Andrzej Gładysiak, Institut des Sciences et Ingénierie Chimiques (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, European Synchrotron Radiation Facility (ESRF), Department of Chemical and Biomolecular Engineering [Los Angeles], University of California [Los Angeles] (UCLA), Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, and Universidad de Granada (UGR)
Subjects: CO2/CH4separation, Materials science, force-field, water, breakthrough curves, gas adsorption, 010402 general chemistry, metal-oranic frameworks, 01 natural sciences, carbon-dioxide capture, crystal, Adsorption, Engineering, hydrophobic channels, Molecule, co2/ch4 separation, General Materials Science, gases, Nanoscience & Nanotechnology, [PHYS]Physics [physics], Molecular interactions, ch4, 010405 organic chemistry, biporous MOFs, 0104 chemical sciences, co2 capture, Chemical engineering, adsorption, CO2/CH4 separation, Chemical Sciences, Metal-organic framework, metal−organic frameworks, simulations, Selectivity
Abstract: International audience; In this work, we report the synthesis of SION-8, a novel metal-organic framework (MOF) based on Ca(II) and a tetracarboxylate ligand TBAPy(4-) endowed with two chemically distinct types of pores characterized by their hydrophobic and hydrophilic properties. By altering the activation conditions, we gained access to two bulk materials: the fully activated SION-8F and the partially activated SION-8P with exclusively the hydrophobic pores activated. SION-8P shows high affinity for both CO2 (Q(st) = 28.4 kJ/mol) and CH4 (Q(st) = 21.4 kJ/mol), while upon full activation, the difference in affinity for CO2 (Q(st) = 23.4 kJ/mol) and CH4 (Q(st) = 16.0 kJ/mol) is more pronounced. The intrinsic flexibility of both materials results in complex adsorption behavior and greater adsorption of gas molecules than if the materials were rigid. Their CO2/CH4 separation performance was tested in fixed-bed breakthrough experiments using binary gas mixtures of different compositions and rationalized in terms of molecular interactions. SION-8F showed a 40-160% increase (depending on the temperature and the gas mixture composition probed) of the CO2/CH4 dynamic breakthrough selectivity compared to SION-8P, demonstrating the possibility to rationally tune the separation performance of a single MOF by manipulating the stepwise activation made possible by the MOF's biporous nature.
Published: 2018
Full Text: View/download PDF

13. n-Heptane cool flame chemistry: Unraveling intermediate species measured in a stirred reactor and motored engine

Author: Salim Sioud, Tao Tao, Misjudeen Raji, Nils Hansen, Zhandong Wang, Lena Ruwe, Katharina Kohse-Höinghaus, Bingjie Chen, David Vuilleumier, Denisia M. Popolan-Vaida, Vijai Shankar Bhavani Shankar, Philippe Dagaut, S. Mani Sarathy, Eike Bräuer, Kai Moshammer, National Synchrotron Radiation Laboratory (NSRL), University of Science and Technology of China [Hefei] (USTC), Clean Combustion Research Center - CCRC (Thuwal, Saudi Arabia), King Abdullah University of Science and Technology (KAUST), Physikalisch-Technische Bundesanstalt [Braunschweig] (PTB), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Universität Bielefeld, Institut de Combustion, Aérothermique, Réactivité et Environnement (ICARE), and Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut des Sciences de l'Ingénierie et des Systèmes (INSIS)
Subjects: General Chemical Engineering, Analytical chemistry, General Physics and Astronomy, Energy Engineering and Power Technology, Atmospheric-pressure chemical ionization, Photoionization, 010402 general chemistry, Mass spectrometry, 7. Clean energy, 01 natural sciences, Aldehyde, chemistry.chemical_compound, peroxides, 0103 physical sciences, synchrotron, Partial oxidation, heptane, ComputingMilieux_MISCELLANEOUS, chemistry.chemical_classification, Engine emissions, Heptane, 010304 chemical physics, Autoxidation, [SPI.FLUID]Engineering Sciences [physics]/Reactive fluid environment, oxidation mechanism, General Chemistry, Cool flame, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Fuel Technology, chemistry, 13. Climate action, jet-stirred reactor, kinetics
Abstract: This work identifies classes of cool flame intermediates from n-heptane low-temperature oxidation in a jet-stirred reactor (JSR) and a motored cooperative fuel research (CFR) engine. The sampled species from the JSR oxidation of a mixture of n-heptane/O2/Ar (0.01/0.11/0.88) were analyzed using a synchrotron vacuum ultraviolet radiation photoionization (SVUV-PI) time-of-flight molecular-beam mass spectrometer (MBMS) and an atmospheric pressure chemical ionization (APCI) Orbitrap mass spectrometer (OTMS). The OTMS was also used to analyze the sampled species from a CFR engine exhaust. Approximately 70 intermediates were detected by the SVUV-PI-MBMS, and their assigned molecular formulae are in good agreement with those detected by the APCI-OTMS, which has ultra-high mass resolving power and provides an accurate elemental C/H/O composition of the intermediate species. Furthermore, the results show that the species formed during the partial oxidation of n-heptane in the CFR engine are very similar to those produced in an ideal reactor, i.e., a JSR. The products can be classified by species with molecular formulae of C7H14Ox (x = 0–5), C7H12Ox (x = 0–4), C7H10Ox (x = 0–4), CnH2n (n = 2–6), CnH2n−2 (n = 4–6), CnH2n+2O (n = 1–4), CnH2nO (n = 1–6), CnH2n−2O (n = 2–6), CnH2n−4O (n = 4–6), CnH2n+2O2 (n = 0–4, 7), CnH2nO2 (n = 1–6), CnH2n−2O2 (n = 2–6), CnH2n−4O2 (n = 4–6), and CnH2nO3 (n = 3–6). The identified intermediate species include alkenes, dienes, aldehyde/keto compounds, olefinic aldehyde/keto compounds, diones, cyclic ethers, peroxides, acids, and alcohols/ethers. Reaction pathways forming these intermediates are proposed and discussed herein. These experimental results are important in the development of more accurate kinetic models for n-heptane and longer-chain alkanes.
Published: 2018
Full Text: View/download PDF

14. Hydration of the sulfate dianion in size-selected water clusters: From SO42−(H2O)9 to SO42−(H2O)13

Author: Evan R. Williams, Richard J. Cooper, Carine Clavaguéra, Ayah A. Hassan, Gilles Ohanessian, Florian Thaunay, Laboratoire de chimie moléculaire (LCM), École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [Berkeley], University of California [Berkeley], and University of California-University of California
Subjects: 010304 chemical physics, Hydrogen bond, Chemistry, Solvation, Analytical chemistry, Infrared spectroscopy, 010402 general chemistry, Condensed Matter Physics, 01 natural sciences, Spectral line, 0104 chemical sciences, 0103 physical sciences, Molecule, Water cluster, Physical and Theoretical Chemistry, Water binding, [CHIM.OTHE]Chemical Sciences/Other, Instrumentation, Spectroscopy, Ion cyclotron resonance
Abstract: International audience; In celebration of Jose Riveros' many essential contributions to gas phase ion chemistry. Keywords: Hydrated sulfate IRPD spectroscopy AMOEBA polarizable force field Second hydration shell Mixed quantum classical modelling O H stretching frequency a b s t r a c t Infrared photodissociation (IRPD) spectra of SO 4 2− (H 2 O) n , n = 9-13, recorded in the cooled cell of a Fourier-transform ion cyclotron resonance mass spectrometer, between 2900 and 3800 cm −1 , are reported. The structures, energetics and infrared spectra of n = 9 and 11-13 were investigated by a combination of classical polarizable molecular dynamics and static quantum chemical calculations. Low-energy structures are mainly determined by the strong structuring effect of the sulfate ion, however, the highest cohesion is achieved when strong water-water interactions are present as well. As a result, the sulfate ion in the most stable structures for n = 9, 11 and 12 is on the surface of the water cluster. While SO 4 2− (H 2 O) 9 involves a mixture of isomers, the other sizes are found to be described by a single structural family, with the most stable structures of SO 4 2− (H 2 O) 11 and SO 4 2− (H 2 O) 13 deriving from that of SO 4 2− (H 2 O) 12 by removal and addition of a water molecule, respectively, without substantial reorganization. An important feature of these structures is that the number of water molecules in the second solvation sphere increases with cluster size, up to 3 for n = 12 and 4 for n = 13. This is directly reflected in the IRPD spectra. All spectra display two main features in the 3150-3350 and 3350-3650 cm −1 range, plus a small band near 3100 cm −1. The 3350-3650 cm −1 massif, which includes most bands arising from second sphere molecules, acquires larger intensity relative to that at 3150-3350 cm −1 which is mainly composed of stretches in first sphere molecules. Whereas most water molecules have ADD coordination (where A stands for acceptor and D stands for donor of a hydrogen bond), special cases, including DD and AADD account for bands at the red and blue ends of the spectra. Computed IR spectra are able to account for most experimental features, especially when anharmonicities are taken into account for the largest red shifts. Finally, the higher abundance of n = 12 relative to other sizes is related to a lower water evaporation rate constant, in good agreement with the water binding energy which is computed to be larger for n = 12 than for 13.
Published: 2017
Full Text: View/download PDF

15. Redox-Initiated Reactivity of Dinuclear β-Diketiminatoniobium Imido Complexes

Author: Kriegel, Benjamin, Naested, Lara, Nocton, Grégory, Lakshmi, K., Lohrey, Trevor, Bergman, Robert, Arnold, John, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Department of Chemistry [Berkeley], University of California [Berkeley], and University of California-University of California
Subjects: [CHIM.INOR]Chemical Sciences/Inorganic chemistry, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2017

16. An experimental and DFT Computational Study of β-Me and β-H elimination coupled with proton transfer; from amides to enamides in Cp*2MX, M = La and Ce

Author: Odile Eisenstein, Richard A. Andersen, Sergio S. Rozenel, Lionel Perrin, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Interface Theory Experiment : Mechanism & Modeling (ITEMM), Institut de Chimie et Biochimie Moléculaires et Supramoléculaires (ICBMS), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie du CNRS (INC)-École Supérieure Chimie Physique Électronique de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie du CNRS (INC)-École Supérieure Chimie Physique Électronique de Lyon-Centre National de la Recherche Scientifique (CNRS), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)
Subjects: Proton, 010405 organic chemistry, Chemistry, Hydride, Stereochemistry, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Organic Chemistry, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, 0104 chemical sciences, Ion, Inorganic Chemistry, chemistry.chemical_compound, Physical and Theoretical Chemistry, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM], Metallocene
Abstract: International audience; The thermal rearrangement of the f-block metallocene amides Cp*2MNR1R2, where R1 is CHMe2, R2 is either CHMe2 or CMe3, and M is either La or Ce, to the corresponding enamides Cp*2MNR1[C(Me)═CH2] and H2 or CH4, respectively, occurs when the solid amides are heated in sealed evacuated ampules at 160–180 °C for 1–2 weeks. The net reaction is a β-H or β-Me elimination followed by a γ-abstraction of a proton at the group from which the β-elimination occurs. When R1 is either SiMe3 or SiMe2CMe3 and R2 is CMe3, the enamide Cp*2MNR1[C(Me)═CH2] is isolated, the result of β-Me elimination, but when R2 is CHMe2, the enamides Cp*2MNR1[C(Me)═CH2] and Cp*2NR1[C(H)═CH2] are isolated, the result of β-H and β-Me elimination. In the latter cases, both enamides are formed in similar amounts and the rates of the β-H and β-Me elimination steps must be similar. A two-step mechanism is developed from DFT calculations. The first step is migration of a hydride or a methyl anion to the Cp*2M fragment, forming M–H or M–Me bonds as the N═C bond in the intermediate imine forms. The enamide evolves from the metal-coordinated imine by abstraction of a proton from the γ-carbon of the intermediate imine. The two elementary steps involve significant geometrical changes within the NαCβCγ set of atoms during the two-step elimination process that are in large part responsible for the relatively high activation barriers for the net reaction, which may be classified as a proton-coupled hydride or methyl anion transfer reaction.
Published: 2017
Full Text: View/download PDF

17. Quantifying similarity of pore-geometry in nanoporous materials

Author: Kathryn Hess, Berend Smit, Pawel Dlotko, Senja Barthel, S. Mohamad Moosavi, Yong Jin Lee, Ecole Polytechnique Fédérale de Lausanne (EPFL), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Understanding the Shape of Data (DATASHAPE), Inria Sophia Antipolis - Méditerranée (CRISAM), Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Inria Saclay - Ile de France, Institut National de Recherche en Informatique et en Automatique (Inria), European Project: 339025,EC:FP7:ERC,ERC-2013-ADG,GUDHI(2014), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)
Subjects: Multidisciplinary, Persistent homology, Similarity (geometry), Materials science, Nanoporous, Science, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, Structure (category theory), General Physics and Astronomy, Geometry, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, General Chemistry, Orders of magnitude (numbers), 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, GeneralLiterature_MISCELLANEOUS, Article, General Biochemistry, Genetics and Molecular Biology, 0104 chemical sciences, Topological data analysis, 0210 nano-technology, A determinant
Abstract: In most applications of nanoporous materials the pore structure is as important as the chemical composition as a determinant of performance. For example, one can alter performance in applications like carbon capture or methane storage by orders of magnitude by only modifying the pore structure. For these applications it is therefore important to identify the optimal pore geometry and use this information to find similar materials. However, the mathematical language and tools to identify materials with similar pore structures, but different composition, has been lacking. We develop a pore recognition approach to quantify similarity of pore structures and classify them using topological data analysis. This allows us to identify materials with similar pore geometries, and to screen for materials that are similar to given top-performing structures. Using methane storage as a case study, we also show that materials can be divided into topologically distinct classes requiring different optimization strategies., Pore structure plays an important role in dictating gas storage performance for nanoporous materials. Here, Smit and colleagues develop a topological approach to quantify pore structure similarity, and exploit the resulting descriptor to screen for materials that possess structural similarities with top-performers.
Published: 2017
Full Text: View/download PDF

18. Carbon-Nitrogen Bond Cleavage by a Thorium-NHC-bpy Complex

Author: Laurent Maron, Stephan Hohloch, John Arnold, Mary E. Garner, Department of Chemistry [Berkeley], University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), University of California [Berkeley], University of California-University of California, Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)
Subjects: Models, Molecular, Stereochemistry, Nitrogen, Isocyanide, Radical, Alkylation, 010402 general chemistry, Crystallography, X-Ray, 01 natural sciences, Catalysis, chemistry.chemical_compound, Bipyridine, 2,2'-Dipyridyl, Heterocyclic Compounds, Carbon–nitrogen bond, Organometallic Compounds, [CHIM]Chemical Sciences, Reactivity (chemistry), Molecular Structure, 010405 organic chemistry, Chemistry, Thorium, General Medicine, General Chemistry, Combinatorial chemistry, Small molecule, Carbon, 3. Good health, 0104 chemical sciences, Chemical bond, Methane
Abstract: International audience; Actinide complexes demonstrate unparalleled reactivity towards small molecules. However, utilizing these powerful transformations in a predictable and deliberate manner remains challenging. Therefore, developing actinide systems that not only perform noteworthy chemistry but also demonstrate controllable reactivity is a key goal. We describe a bis(NHC)borate thorium‐bpy complex (1) that is capable of reductively cleaving the R−NC bond in a series of organic isocyanides. In contrast to most actinide‐mediated bond activations, the dealkylation event mediated by 1 is remarkably general and yields very well‐defined products that assist in mechanistic elucidation. Synthesis of the rearranged but‐3‐enyl product from the reaction of 1 and cyclopropylmethyl isocyanide supports the notion of a radical‐based mechanism.
Published: 2016

19. A New Supporting Ligand in Actinide Chemistry Leads to Reactive Bis(NHC)borate-Supported Thorium Complexes

Author: John Arnold, Laurent Maron, Stephan Hohloch, Mary E. Garner, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Actinide chemistry, 010405 organic chemistry, Ligand, Organic Chemistry, Thorium, chemistry.chemical_element, 010402 general chemistry, Photochemistry, 01 natural sciences, Medicinal chemistry, 0104 chemical sciences, Inorganic Chemistry, chemistry.chemical_compound, chemistry, [CHIM]Chemical Sciences, Chelation, Reactivity (chemistry), Singlet state, Physical and Theoretical Chemistry, Carbene, Derivative (chemistry)
Abstract: International audience; A versatile, monoanionic, chelating (bis)carbene ligand (2) was used to prepare a thorium dihalide complex (3) and a direduced-bpy derivative (4). CASSCF calculations suggest the involvement of a multiconfigurational open-shell singlet, with the main configuration corresponding to a Th(III)-bpy(−1) (f1π*1) electronic structure. The reactivity of 4 was explored in various transformations, including reactions with carbonyls and organic azides; the latter gave rise to an unusual terminal Th-imido bpy complex (6).
Published: 2016

20. Photo-activation of d 0 niobium imido azides: en route to nitrido complexes

Author: Clément CAMP, Grant, Lauren N., Bergman, Robert G., John Arnold, Laboratoire de Chimie, Catalyse, Polymères et Procédés, R 5265 (C2P2), Centre National de la Recherche Scientifique (CNRS)-École supérieure de Chimie Physique Electronique de Lyon (CPE)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC), Department of Chemistry [Berkeley], University of California [Berkeley], and University of California-University of California
Subjects: [CHIM]Chemical Sciences, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2016

21. MCTDHB physics and technologies: Excitations and vorticity, single-shot detection, measurement of fragmentation, and optimal control in correlated ultra-cold bosonic many-body Systems

Author: Tommaso Calarco, Antonio Negretti, Raphael Beinke, Alexej I. Streltsov, Lorenz S. Cederbaum, Oksana I. Streltsova, Kaspar Sakmann, Vanderlei Salvador Bagnato, Ioannis Brouzos, Tommaso Caneva, Simone Montangero, Tomos Wells, Ressa S. Said, Marcus Theisen, Shachar Klaiman, Ofir E. Alon, Storm E. Weiner, Mark A. Kasevich, Marios C. Tsatsos, Axel U. J. Lode, Department of Mathematics-Physics [Haifa at Oranim], University of Haifa [Haifa], Institute of Physics [São Paulo], University of São Paulo (USP), Theoretische Chemie Universität Heidelberg, Universität Heidelberg [Heidelberg], Universität Ulm - Ulm University [Ulm, Allemagne], Institute for Complex Quantum Systems (ICQ), Institut de Ciencies Fotoniques [Castelldefels] (ICFO), Department of Physics [Basel], University of Basel (Unibas), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Department of Mathematics [Cambridge] (HARVARD), and Harvard University [Cambridge]
Subjects: Physics, [PHYS]Physics [physics], Computer Science (all), Physics and Astronomy (all), Mathematics (all), Chemistry (all), Quantum dynamics, Hartree, Vorticity, Optimal control, 01 natural sciences, 010305 fluids & plasmas, Vortex, Classical mechanics, MCTDH, 0103 physical sciences, [CHIM]Chemical Sciences, Statistical physics, 010306 general physics, Quantum, ComputingMilieux_MISCELLANEOUS, Boson, Coherence (physics)
Abstract: Here we report on further applications, developments, expansion, and proliferation of the Multi-Configurational Time-Dependent Hartree for Bosons (MCTDHB) method in the context of ultra-cold atomic systems. In this year we put our main efforts to understanding and generalizing vortices—two-dimensional (2D) and three-dimensional (3D) quantum objects carrying angular momentum—from the perspective of the many-body physics. We have studied static properties and quantum dynamics of vortices confined in simple parabolic traps and in circular traps. Particular emphasis has been put on the loss of coherence and build-up of the fragmentation. Complimentary, we continue to develop the MCTDHB method spanning several directions of the theoretical and computational physics as well as optimal-control theory: (a) the linear-response on-top of the MCTDHB method (LR-MCTDHB) has been reformulated in a compact block form, expanded for general inter-particle interactions, and benchmarked against the exactly-solvable harmonic-interaction model; (b) a new analysis tool capable of simulating the outcomes of typical shots generated in the experimental detection of ultra-cold atomic systems has been invented, tested, and applied; (c) a novel algorithm offering a direct quantitative measurement of the possible fragmentation in bosonic systems has been proposed and applied; (d) the optimal-control Chopped RAndom Basis (CRAB) algorithm has been merged with the MCTDHB package and applied to manipulate quantum systems. Implications and further perspectives and future research plans are briefly discussed and addressed.
Published: 2016
Full Text: View/download PDF

22. Homoleptic two-coordinate silylamido complexes of chromium(I), manganese(I), and cobalt(I)

Author: Philip C. Bunting, Sébastien Bontemps, Laure Vendier, Sylviane Sabo-Etienne, Mihail Atanasov, Elizaveta A. Suturina, Jeffrey R. Long, C. Gunnar Werncke, Frank Neese, Laboratoire de chimie de coordination (LCC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Max Planck Institute for Chemical Energy Conversion, Max-Planck-Gesellschaft, Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA, affiliation inconnue, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Institute of General and Inorganic Chemistry, and Bulgarian Academy of Sciences (BAS)
Subjects: Steric effects, 010405 organic chemistry, Chemistry, Ligand, Stereochemistry, Dimer, Organic Chemistry, General Chemistry, Nuclear magnetic resonance spectroscopy, 010402 general chemistry, 01 natural sciences, Magnetic susceptibility, Catalysis, 0104 chemical sciences, Crystallography, chemistry.chemical_compound, Molecule, Reactivity (chemistry), [CHIM.COOR]Chemical Sciences/Coordination chemistry, Homoleptic
Abstract: International audience; Anionic two-coordinate complexes of first-row transition-metal(I) centres are rare molecules that are expected to reveal new magnetic properties and reactivity. Recently, we demonstrated that a N(SiMe3)(2)(-) ligand set, which is unable to prevent dimerisation or extraneous ligand coordination at the +2 oxidation state of iron, was nonetheless able to stabilise anionic two-coordinate Fe-I complexes even in the presence of a Lewis base. We now report analogous Cr-I and Co-I complexes with exclusively this amido ligand and the isolation of a [Mn-IN(SiMe3)(2)(2)](2)(2-) dimer that features a Mn Mn bond. Additionally, by increasing the steric hindrance of the ligand set, the two-coordinate complex [Mn-IN(Dipp)(SiMe3)(2)](-) was isolated (Dipp= 2,6-iPr(2)-C6H3). Characterisation of these compounds by using X-ray crystallography, NMR spectroscopy, and magnetic susceptibility measurements is provided along with ligand-field analysis based on CASSCF/NEVPT2 ab initio calculations.
Published: 2016
Full Text: View/download PDF

23. Multifaceted magnetization dynamics in the mononuclear complex [ReIVCl4(CN)2]2

Author: David Aguilà, Marc Sigrist, Dumitru Samohvalov, Ming-Liang Tong, Jeffrey R. Long, Jesper Bendix, Karsten Holldack, Jun-Liang Liu, Alexander Schnegg, Hannu Mutka, Joscha Nehrkorn, Xiaowen Feng, Kasper S. Pedersen, Rodolphe Clérac, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, MOE Key Lab of Bioinorganic and Synthetic Chemistry, Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB), Berlin Joint EPR Laboratory, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (Helmholtz-Zentrum Berlin), Helmholtz-Zentrum Berlin, Department of Chemistry [Copenhagen], Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Institut Laue-Langevin (ILL), ILL, Institute of Chemistry, Academia Sinica, Centre de Recherche Paul Pascal (CRPP), Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Materials Science Division [LBNL Berkeley], Lawrence Berkeley National Laboratory [Berkeley] (LBNL), and National Science Foundation (NSF) under Grant CHE-1464841, the CNRS (PICS No.06485), the University of Bordeaux, the Conseil Regional d’Aquitaine, the ANR, the French Embassy in the US (Chateaubriand fellowship for X. F.), the GdR MCM-2 and Sun Yat-Sen University (the International Program of Project 985 for J.-L. L.).K. S. P. thanks the Danish Research Council for Independent Research for a DFF-Sapere Aude Research Talent grant (4090-00201). The low temperature crystal structure was collected at the Stanford Nano Shared Facilities (SNSF), supported by theNSF under award ECCS-1542152.
Subjects: Magnetization dynamics, 010405 organic chemistry, Chemistry, Relaxation (NMR), Metals and Alloys, Relaxation process, Large scale facilities for research with photons neutrons and ions, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 01 natural sciences, Catalysis, Inelastic neutron scattering, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, law.invention, Nuclear magnetic resonance, law, Chemical physics, Materials Chemistry, Ceramics and Composites, Electron paramagnetic resonance
Abstract: International audience; The mononuclear complex (Bu4N)2[ReIVCl4(CN)2].2DMA (DMA =N,N-dimethylacetamide) displays intricate magnetization dynamics, implying Orbach, direct, and Raman-type relaxation processes. The Orbach relaxation process is characterized by an energy barrier of 39 K (27 cm-1) that is discussed based on high-field electron paramagnetic resonance (EPR), inelastic neutron scattering and frequency domain THz EPR investigations.
Published: 2016
Full Text: View/download PDF

24. Donor-Promoted 1,2-Hydrogen Migration from Silicon to a Saturated Ruthenium Center and Access to Silaoxiranyl and Silaiminyl Complexes

Author: Odile Eisenstein, Christophe Raynaud, T. Don Tilley, Hsueh-Ju Liu, Clark R. Landis, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)
Subjects: Silanes, Chemistry, Silylene, chemistry.chemical_element, General Chemistry, [CHIM.INOR]Chemical Sciences/Inorganic chemistry, Photochemistry, Biochemistry, Medicinal chemistry, Catalysis, 3. Good health, Ruthenium, chemistry.chemical_compound, Electron transfer, Colloid and Surface Chemistry, Deprotonation, Tosyl, Benzophenone, Reactivity (chemistry)
Abstract: International audience; Masked silylene complexes Cp*(IXy-H)(H)RuSiH2R (R = Mes (3) and Trip (4); IXy = 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene; “IXy-H” is the deprotonated form of IXy) exhibit metallosilylene-like (LnM–Si–R) reactivity, as observed in reactions of nonenolizable ketones, enones, and tosyl azides, to give unprecedented silaoxiranyl, oxasilacyclopentenyl, and silaiminyl complexes, respectively. Notably, these silicon-containing complexes are derived from the primary silanes MesSiH3 and TripSiH3 via activation of all three Si–H bonds. DFT calculations suggest that the mechanism of formation for the silaoxiranyl complex Cp*(IXy)(H)2Ru–Si(OCPh2)Trip (6) involves coordination of benzophenone to a silylene silicon atom, followed by a single-electron transfer in which Si-bonded, non-innocent benzophenone accepts an electron from the reactive, electron-rich ruthenium center. Importantly, this electron transfer promotes an unusual 1,2-hydrogen migration to the resulting, more electron-deficient ruthenium center via a diradicaloid transition state.
Published: 2015
Full Text: View/download PDF

25. Stochastic dynamics of collective modes for Brownian dipoles

Author: Frédéric van Wijland, Leticia F. Cugliandolo, Pierre-Michel Déjardin, Gustavo S. Lozano, Laboratoire de Physique Théorique et Hautes Energies (LPTHE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), LAboratoire de Mathématiques et PhySique (LAMPS), Université de Perpignan Via Domitia (UPVD), Departamento de Física [Buenos Aires], Facultad de Ciencias Exactas y Naturales [Buenos Aires] (FCEyN), Universidad de Buenos Aires [Buenos Aires] (UBA)-Universidad de Buenos Aires [Buenos Aires] (UBA), Matière et Systèmes Complexes (MSC (UMR_7057)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, LAboratoire de Modélisation Pluridisciplinaire et Simulations (LAMPS), Matière et Systèmes Complexes (MSC), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)
Subjects: Ciencias Físicas, FOS: Physical sciences, Dipoles, Condensed Matter - Soft Condensed Matter, Space (mathematics), 7. Clean energy, purl.org/becyt/ford/1 [https], Stochastic differential equation, Statistical physics, Colloids, Condensed Matter - Statistical Mechanics, Brownian motion, Physics, [PHYS]Physics [physics], Statistical Mechanics (cond-mat.stat-mech), Brownian, purl.org/becyt/ford/1.3 [https], Langevin equation, Astronomía, Classical mechanics, Brownian dynamics, Soft Condensed Matter (cond-mat.soft), Density functional theory, Brillouin and Langevin functions, Rotation (mathematics), CIENCIAS NATURALES Y EXACTAS
Abstract: The individual motion of a colloidal particle is described by an overdamped Langevin equation. When rotational degrees of freedom are relevant, these are described by a corresponding Langevin process. Our purpose is to show that the microscopic local density of colloids, in terms of a space and rotation state, also evolves according to a Langevin equation. The latter can then be used as the starting point of a variety of approaches, ranging from dynamical density functional theory to mode-coupling approximations. Fil: Cugliandolo, Leticia Fernanda. Universite Pierre et Marie Curie; Francia Fil: Déjardin, Pierre Michel. Université de Perpignan Via Domitia; Francia Fil: Lozano, Gustavo Sergio. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Van Wijland, Frédéric. Université Paris Diderot - Paris 7; Francia. University of California at Berkeley; Estados Unidos
Published: 2015
Full Text: View/download PDF

26. Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Author: Kristina D. Closser, Trilisa M. Perrine, Tamar Stein, Vitaly A. Rassolov, Roberto Peverati, Alexander Prociuk, William A. Goddard, Barry D. Dunietz, Henry F. Schaefer, Ilya Kaliman, Sina Yeganeh, Martin Head-Gordon, Ben Albrecht, Mark A. Watson, Donald G. Truhlar, Joseph E. Subotnik, Dmytro Kosenkov, Andreas Klamt, Andrew Behn, Caroline M. Krauter, Zhengting Gan, Jia Deng, Bernard R. Brooks, Darragh P. O’Neill, Yan Zhao, David Casanova, Arieh Warshel, Christopher J. Cramer, John M. Herbert, Richard G. Edgar, Yu-Chuan Su, Simon A. Maurer, Andrew T. B. Gilbert, Joseph Gomes, C. David Sherrill, Eric Neuscamman, Michael Wormit, Ethan Alguire, Ryan P. Steele, Yousung Jung, David W. Small, Keith V. Lawler, Eric J. Sundstrom, Tao Wang, Edward G. Hohenstein, Jae-Hoon Kim, Phil Klunzinger, Andreas Dreuw, Paul R. Horn, Alexander J. Sodt, Dirk R. Rehn, Tomasz Kuś, Shaama Mallikarjun Sharada, Ryan M. Richard, Xing Zhang, Roberto Olivares-Amaya, Jan Wenzel, Chao-Ping Hsu, David Stück, Joerg Kussmann, Brian J. Austin, Andreas W. Hauser, Narbe Mardirossian, Leslie Vogt, Debashree Ghosh, Emil Proynov, John Parkhill, Ksenia B. Bravaya, Magnus W. D. Hanson-Heine, Alán Aspuru-Guzik, Young Min Rhee, Zhi-Qiang You, WanZhen Liang, Arie Landau, An Ghysels, Rollin A. King, Jie Liu, Hainam Do, Deborah L. Crittenden, Kirill Khistyaev, Peter Gill, Thomas R. Furlani, Daniel S. Lambrecht, Oleg A. Vydrov, Sandeep Sharma, Lyudmila V. Slipchenko, Shervin Fatehi, Kai Brandhorst, Fenglai Liu, Christopher F. Williams, Yves A. Bernard, Jihan Kim, Laszlo Fusti-Molnar, Shane R. Yost, Xintian Feng, Evgeny Epifanovsky, Troy Van Voorhis, Philipp H. P. Harbach, Alec F. White, Shawn T. Brown, Alex J. W. Thom, Xin Xu, Eric J. Berquist, Rohini C. Lochan, Alexis T. Bell, Thomas-C. Jagau, Adèle D. Laurent, Ester Livshits, Jun Yang, Michael W. Schmidt, H. Lee Woodcock, Steven R. Gwaltney, Roi Baer, Garnet Kin-Lic Chan, Dmitry Zuev, Zachary C. Holden, Vitalii Vanovschi, Takashi Tsuchimochi, Nicholas J. Russ, Aleksandr V. Marenich, Adrian W. Lange, Yihan Shao, C. Melania Oana, Anthony D. Dutoi, Robert A. DiStasio, Leif D. Jacobson, Jing Kong, Yunqing Chen, Michael Diedenhofen, Anna Golubeva-Zadorozhnaya, Mary A. Rohrdanz, Warren J. Hehre, Arne Luenser, Prashant Uday Manohar, Ka Un Lao, Nicholas J. Mayhall, Rustam Z. Khaliullin, Edina Rosta, Samuel F. Manzer, Tim Kowalczyk, Sergey V. Levchenko, Nicholas A. Besley, Benjamin Kaduk, Shan-Ping Mao, Matthew Goldey, Daniel M. Chipman, Anna I. Krylov, Mark S. Gordon, Igor Ying Zhang, Jeng-Da Chai, Siu Hung Chien, Hyunjun Ji, Gregory J. O. Beran, Ching Yeh Lin, Paul M. Zimmerman, Christian Ochsenfeld, Chun-Min Chang, Institut für Physikalische Chemie, Universität Mainz, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, China Earthquake Networks Center, China Earthquake Administration (CEA), University of Minnesota System, Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, COSMOlogic GmbH & Co KG, Institute of Physical and Theoretical Chemistry, Universität Regensburg (UR), Department of Chemistry, Minnesota Supercomputing Institute, and Chemical Theory Center, Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174) (FEMTO-ST), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS), University of Frankfurt, Department of Mathematics [Shanghai], Shanghai Jiao Tong University [Shanghai], Chemistry, Ludwig-Maximilians-Universität München (LMU), Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, Chaire Sciences des Systèmes et Défis Energétiques EDF/ECP/Supélec (SSEC), Ecole Centrale Paris-Ecole Supérieure d'Electricité - SUPELEC (FRANCE)-CentraleSupélec-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Chimie Et Interdisciplinarité : Synthèse, Analyse, Modélisation (CEISAM), Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Université de Technologie de Belfort-Montbeliard (UTBM)-Ecole Nationale Supérieure de Mécanique et des Microtechniques (ENSMM)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC), and Université de Nantes (UN)-Université de Nantes (UN)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, electronic structure theory, Orbital-free density functional theory, software, Implicit solvation, Intermolecular force, computational modelling, Biophysics, electron correlation, Condensed Matter Physics, Quantum chemistry, quantum chemistry, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Coupled cluster, Atomic orbital, Quantum mechanics, Excited state, Density functional theory, Statistical physics, Physical and Theoretical Chemistry, Q-Chem, Molecular Biology, density functional theory
Abstract: International audience; A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Moller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr-2 dimer, exploring zeolite-catalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube.
Published: 2015
Full Text: View/download PDF

27. Electron localization in a mixed-valence diniobium benzene complex

Author: Gianetti, Thomas, Nocton, Grégory, Minasian, Stefan, Kaltsoyannis, Nikolas, Kozimor, A., Shuh, David, Tyliszczak, Tolek, Bergman, Robert, Arnold, John, Tard, Cédric, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Laboratoire de chimie moléculaire (LCM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Chemistry Division, Los Alamos National Laboratory, Los Alamos National Laboratory (LANL), University College of London [London] (UCL), and Advanced Light Source [LBNL Berkeley] (ALS)
Subjects: [CHIM.OTHE] Chemical Sciences/Other, [CHIM.OTHE]Chemical Sciences/Other, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2015

28. 1,2-Hydrogen Migration to a Saturated Ruthenium Complex via Reversal of Electronic Properties for Tin in a Stannylene-to-Metallostannylene Conversion

Author: Odile Eisenstein, T. Don Tilley, Thomas Davin, Hsueh-Ju Liu, Christophe Raynaud, Julie Guihaumé, Department of Chemistry [Berkeley], University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de chimie théorique (LCT), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), University of California [Berkeley], University of California-University of California, and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)
Subjects: Hydrogen, Chemistry, Ligand, chemistry.chemical_element, Electron donor, General Chemistry, Photochemistry, Biochemistry, Acceptor, Catalysis, Ruthenium, Metal, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, Colloid and Surface Chemistry, Intramolecular force, visual_art, visual_art.visual_art_medium, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Tin
Abstract: International audience; An intramolecular 1,2(α)-H migration in a saturated ruthenium stannylene complex, to form a ruthenostannylene complex, involves a reversal of the role for a coordinated stannylene ligand, from that of an electron donor to an acceptor in the transition state. This change in the bonding properties for a stannylene group, with a simple molecular motion, lifts the usual requirement for generation of an unsaturated metal center in migration chemistry.
Published: 2014
Full Text: View/download PDF

29. Cyclometalated N-Heterocyclic Carbene Complexes of Ruthenium for Access to Electron-Rich Silylene Complexes That Bind the Lewis Acids CuOTf and AgOTf

Author: T. Don Tilley, Odile Eisenstein, Hsueh-Ju Liu, Christophe Raynaud, Department of Chemistry [Berkeley], University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de chimie théorique (LCT), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), University of California [Berkeley], University of California-University of California, and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)
Subjects: 010405 organic chemistry, Stereochemistry, Silylene, chemistry.chemical_element, General Chemistry, 010402 general chemistry, 01 natural sciences, Biochemistry, Catalysis, Cycloaddition, 0104 chemical sciences, Ruthenium, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, Colloid and Surface Chemistry, Deprotonation, chemistry, Reactivity (chemistry), [CHIM.COOR]Chemical Sciences/Coordination chemistry, Lewis acids and bases, Carbene, Bond cleavage
Abstract: International audience; The synthesis of the cyclometalated complexes Cp*Ru(IXy-H) (2) [IXy = 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene; IXy-H = 1-(2-CH2C6H3-6-methyl)-3-(2,6-dimethylphenyl)imidazol-2-ylidene-1-yl (the deprotonated form of IXy); Cp* = η5-C5Me5] and Cp*Ru(IXy-H)(N2) (3) was achieved by dehydrochlorination of Cp*Ru(IXy)Cl (1) with KCH2Ph. Complexes 2 and 3 activate primary silanes (RSiH3) to afford the silyl complexes Cp*(IXy-H)(H)RuSiH2R [R = p-Tol (4), Mes (5), Trip (6)]. Density functional theory studies indicated that these complexes are close in energy to the corresponding isomeric silylene species Cp*(IXy)(H)Ru═SiHR. Indeed, reactivity studies indicated that various reagents trap the silylene isomer of 6, Cp*(IXy)(H)Ru═SiHTrip (6a). Thus, benzaldehyde reacts with 6 to give the [2 + 2] cycloaddition product 7, while 4-bromoacetophenone reacts via C-H bond cleavage and formation of the enolate Cp*(IXy)(H)2RuSiH[OC(═CH2)C6H4Br]Trip (8). Addition of the O-H bond of 2,6-dimethylphenol across the Ru═Si bond of 6a gives Cp*(IXy)(H)2RuSiH(2,6-Me2C6H3O)Trip (9). Interestingly, CuOTf and AgOTf also react with 6 to provide unusual Lewis acid-stabilized silylene complexes in which MOTf bridges the Ru-Si bond. The AgOTf complex, which was crystallographically characterized, exhibits a structure similar to that of [Cp*(iPr3P)Ru(μ-H)2SiHMes]+, with a three-center, two-electron Ru-Ag-Si interaction. Natural bond orbital analysis of the MOTf complexes supported this type of bonding and characterized the donor interaction with Ag (or Cu) as involving a delocalized interaction with contributions from the carbene, silylene, and hydride ligands of Ru.
Published: 2014
Full Text: View/download PDF

30. CO2 Adsorption in Fe2(dobdc): A Classical Force Field Parameterized from Quantum Mechanical Calculations

Author: Eric D. Bloch, David Semrouni, Kyuho Lee, Laura Gagliardi, Rémi Maurice, Berend Smit, Joshua Borycz, Li-Chiang Lin, Jihan Kim, Allison L. Dzubak, Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, Department of Chemical and Biomolecular Engineering, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Korea Advanced Institute of Science and Technology (KAIST), Laboratoire SUBATECH Nantes (SUBATECH), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes)
Subjects: Chemistry, Monte Carlo method, Thermodynamics, Parameterized complexity, Interaction energy, Co2 adsorption, Force field (chemistry), Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, General Energy, Adsorption, Computational chemistry, Molecule, Physical and Theoretical Chemistry, Quantum
Abstract: Carbon dioxide adsorption isotherms have been computed for the metal–organic framework (MOF) Fe2(dobdc), where dobdc4– = 2,5-dioxido-1,4-benzenedicarboxylate. A force field derived from quantum mechanical calculations has been used to model adsorption isotherms within a MOF. Restricted open-shell Moller–Plesset second-order perturbation theory (ROMP2) calculations have been performed to obtain interaction energy curves between a CO2 molecule and a cluster model of Fe2(dobdc). The force field parameters have been optimized to best reproduced these curves and used in Monte Carlo simulations to obtain CO2 adsorption isotherms. The experimental loading of CO2 adsorbed within Fe2(dobdc) was reproduced quite accurately. This parametrization scheme could easily be utilized to predict isotherms of various guests inside this and other similar MOFs not yet synthesized.
Published: 2014
Full Text: View/download PDF

31. Activation of White Phosphorus by Low-Valent Group 5 Complexes: Formation and Reactivity of cyclo-P4 Inverted Sandwich Compounds

Author: Laurent Maron, John Arnold, Clément Camp, Robert G. Bergman, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Phosphide, Stereochemistry, Tantalum, chemistry.chemical_element, Protonation, Electronic structure, Crystallography, X-Ray, 010402 general chemistry, 01 natural sciences, Biochemistry, Article, Catalysis, law.invention, chemistry.chemical_compound, Colloid and Surface Chemistry, Hydrogenolysis, law, Coordination Complexes, Molecule, [CHIM]Chemical Sciences, Computer Simulation, Electron paramagnetic resonance, ComputingMilieux_MISCELLANEOUS, Crystallography, Molecular Structure, 010405 organic chemistry, Phosphorus, General Chemistry, 0104 chemical sciences, Dication, chemistry, Cyclization, Chemical Sciences, X-Ray, Oxidation-Reduction
Abstract: We report the synthesis and comprehensive study of the electronic structure of a unique series of dinuclear group 5 cyclo-tetraphosphide inverted sandwich complexes. White phosphorus (P4) reacts with niobium(III) and tantalum(III) β-diketiminate (BDI) tert-butylimido complexes to produce the bridging cyclo-P4 phosphide species {[(BDI)(N(t)Bu)M]2(μ-η(3):η(3)P4)} (1, M = Nb; 2, M = Ta) in fair yields. 1 is alternatively synthesized upon hydrogenolysis of (BDI)Nb(N(t)Bu)Me2 in the presence of P4. The trinuclear side product {[(BDI)NbN(t)Bu]3(μ-P12)} (3) is also identified. Protonation of 1 with [HOEt2][B(C6F5)4] does not occur at the phosphide ring but rather involves the BDI ligand to yield {[(BDI(#))Nb(N(t)Bu)]2(μ-η(3):η(3)P4)}[B(C6F5)4]2 (4). The monocation and dication analogues {[(BDI)(N(t)Bu)Nb]2(μ-η(3):η(3)P4)}{B(Ar(F))4}n (5, n = 1; 6, n = 2) are both synthesized by oxidation of 1 with AgBAr(F). DFT calculations were used in combination with EPR and UV-visible spectroscopies to probe the nature of the metal-phosphorus bonding.
Published: 2014

32. Unusual activation of H 2 by reduced cobalt complexes supported by a PNP pincer ligand

Author: Rozenel, Sergio S., Rosa Padilla, Clément CAMP, John Arnold, Department of Chemistry [Berkeley], University of California [Berkeley], and University of California-University of California
Subjects: [CHIM]Chemical Sciences, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2014

33. Single-Ion Magnetic Anisotropy and Isotropic Magnetic Couplings in the Metal–Organic Framework Fe2(dobdc)

Author: Laura Gagliardi, Rémi Maurice, Joshua Borycz, Pragya Verma, Donald G. Truhlar, Joseph M. Zadrozny, Sijie Luo, Jeffrey R. Long, Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, Department of Chemistry [Berkeley], University of California [Berkeley], and University of California-University of California
Subjects: Models, Molecular, Phthalic Acids, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, k-nearest neighbors algorithm, Ion, Inorganic Chemistry, Cluster (physics), Ferrous Compounds, Physical and Theoretical Chemistry, Anisotropy, ComputingMilieux_MISCELLANEOUS, Ions, Condensed matter physics, Chemistry, Isotropy, Temperature, 021001 nanoscience & nanotechnology, 3. Good health, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Magnetic anisotropy, Magnetic Fields, Metal-organic framework, 0210 nano-technology, Selectivity
Abstract: The metal-organic framework Fe2(dobdc) (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate), often referred to as Fe-MOF-74, possesses many interesting properties such as a high selectivity in olefin/paraffin separations. This compound contains open-shell Fe(II) ions with open coordination sites which may have large single-ion magnetic anisotropies, as well as isotropic couplings between the nearest and next nearest neighbor magnetic sites. To complement a previous analysis of experimental data made by considering only isotropic couplings [Bloch et al. Science 2012, 335, 1606], the magnitude of the main magnetic interactions are here assessed with quantum chemical calculations performed on a finite size cluster. It is shown that the single-ion anisotropy is governed by same-spin spin-orbit interactions (i.e., weak crystal-field regime), and that this effect is not negligible compared to the nearest neighbor isotropic couplings. Additional magnetic data reveal a metamagnetic behavior at low temperature. This effect can be attributed to various microscopic interactions, and the most probable scenarios are discussed.
Published: 2013
Full Text: View/download PDF

34. Thermal Dihydrogen Elimination from Cp☆2Yb(4,5-diazafluorene)

Author: Laurent Maron, Richard A. Andersen, Grégory Nocton, Corwin H. Booth, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Magnetic moment, 010405 organic chemistry, Chemistry, Organic Chemistry, 010402 general chemistry, 01 natural sciences, XANES, 0104 chemical sciences, Adduct, Inorganic Chemistry, Computational chemistry, Atom, Physical chemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Complete active space, Physical and Theoretical Chemistry, Triplet state, Spectroscopy, Bimetallic strip
Abstract: International audience; The reaction of 4,5-diazafluorene with Cp*2Yb(OEt2), where Cp* is pentamethylcyclopentadienyl, affords the isolable adduct Cp*2Yb(4,5-diazafluorene) (1), which slowly eliminates H2 to form Cp*2Yb(4,5-diazafluorenyl) (2); the net reaction is therefore 1 → 2 + H*. The ytterbium atom in 1 is shown to be intermediate valent by variable-temperature LIII-edge X-ray absorption near-edge (XANES) spectroscopy, consistent with its low effective magnetic moment (μeff). The experimental studies are supported by complete active space self-consistent field (CASSCF) calculations, showing that two open-shell singlets lie below the triplet state. The two open-shell singlets are calculated to be multiconfigurational and closely spaced, in agreement with the observed temperature dependence of the XANES and χ data, which are fit to a Boltzmann distribution. A mechanism for dihydrogen formation is proposed on the basis of kinetic and labeling studies to involve the bimetallic complex (Cp*2Yb)2(4,5-diazafluorenyl)2, in which the heterocyclic amine ligands are joined by a carbon-carbon bond at C(9)-C(9′).
Published: 2013
Full Text: View/download PDF

35. Diniobium Inverted Sandwich Complexes with µ-η6:η6-Arene Ligands: Synthesis, Kinetics of Formation, and Electronic Structure

Author: A. L. David Kilcoyne, Stosh A. Kozimor, Thomas L. Gianetti, Stefan G. Minasian, Tolek Tyliszczak, John Arnold, Grégory Nocton, David K. Shuh, Neil C. Tomson, Robert G. Bergman, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Laboratoire Hétéroéléments et Coordination (DCPH), École polytechnique (X)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Chemistry Division, Los Alamos National Laboratory, Los Alamos National Laboratory (LANL), Advanced Light Source [LBNL Berkeley] (ALS), and Lawrence Berkeley National Laboratory [Berkeley] (LBNL)
Subjects: 010405 organic chemistry, Chemistry, Stereochemistry, Kinetics, Cationic polymerization, Protonation, General Chemistry, Electronic structure, 010402 general chemistry, 01 natural sciences, Biochemistry, Small molecule, Catalysis, XANES, 0104 chemical sciences, Crystallography, Colloid and Surface Chemistry, Reactivity (chemistry), [CHIM.COOR]Chemical Sciences/Coordination chemistry, Absorption (chemistry)
Abstract: Monometallic niobium arene complexes [Nb(BDI)(N(t)Bu)(R-C(6)H(5))] (2a: R = H and 2b: R = Me, BDI = N,N'-diisopropylbenzene-β-diketiminate) were synthesized and found to undergo slow conversion into the diniobium inverted arene sandwich complexes [[(BDI)Nb(N(t)Bu)](2)(μ-RC(6)H(5))] (7a: R = H and 7b: R = Me) in solution. The kinetics of this reaction were followed by (1)H NMR spectroscopy and are in agreement with a dissociative mechanism. Compounds 7a-b showed a lack of reactivity toward small molecules, even at elevated temperatures, which is unusual in the chemistry of inverted sandwich complexes. However, protonation of the BDI ligands occurred readily on treatment with [H(OEt(2))][B(C(6)F(5))(4)], resulting in the monoprotonated cationic inverted sandwich complex 8 [[(BDI(#))Nb(N(t)Bu)][(BDI)Nb(N(t)Bu)](μ-C(6)H(5))][B(C(6)F(5))(4)] and the dicationic complex 9 [[(BDI(#))Nb(N(t)Bu)](2)(μ-RC(6)H(5))][B(C(6)F(5))(4)](2) (BDI(#) = (ArNC(Me))(2)CH(2)). NMR, UV-vis, and X-ray absorption near-edge structure (XANES) spectroscopies were used to characterize this unique series of diamagnetic molecules as a means of determining how best to describe the Nb-arene interactions. The X-ray crystal structures, UV-vis spectra, arene (1)H NMR chemical shifts, and large J(CH) coupling constants provide evidence for donation of electron density from the Nb d-orbitals into the antibonding π system of the arene ligands. However, Nb L(3,2)-edge XANES spectra and the lack of sp(3) hybridization of the arene carbons indicate that the Nb → arene donation is not accompanied by an increase in Nb formal oxidation state and suggests that 4d(2) electronic configurations are appropriate to describe the Nb atoms in all four complexes.
Published: 2013
Full Text: View/download PDF

36. Actinide separations using ionic exchange and extraction chromatography resins

Author: Champion, Julie, Shusterman, Jennifer, Gantz, Erin, Uribe, Eva, Ellison, Paul, Nitsche, Heino, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Laboratoire SUBATECH Nantes (SUBATECH), and Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [CHIM.RADIO]Chemical Sciences/Radiochemistry, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2012

37. Cyanido-bridged one-dimensional systems assembled from [ReIVCl4(CN)2]2- and [MII(cyclam)]2+ (M = Ni, Cu) precursors

Author: Céline Pichon, Pierre Dechambenoit, Indrani Bhowmick, Rodolphe Clérac, Ie Rang Jeon, Elizabeth A. Hillard, T. David Harris, Centre de recherches Paul Pascal (CRPP), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [Berkeley], University of California [Berkeley], and University of California-University of California
Subjects: Diffraction, crystal structure, 010405 organic chemistry, Metal ions in aqueous solution, General Chemistry, Crystal structure, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 01 natural sciences, Magnetic susceptibility, 0104 chemical sciences, Crystal, Crystallography, chemistry.chemical_compound, chemistry, Ferromagnetism, cyanido-based materials, Cyclam, Antiferromagnetism, molecular magnets, magnetic properties
Abstract: 8 pages; International audience; Three new cyanido-bridged heterometallic ReIVNiII and ReIVCuII one-dimensional systems were synthesized and extensively characterized both structurally and magnetically. Single-crystal X-ray diffraction analysis revealed that these compounds display a common topology, with chains composed of alternating [ReIVCl4(CN)2]2- and [MII(cyclam)]2+ (M = Ni in 1, Cu in 2) or [CuII(N,N′-dimethylcyclam)]2+ (in 3) building units. Two different chain orientations with a tilt angle of ca. 51° to 55° are present in the crystal packing of these compounds. The magnetic susceptibility measurements suggest the presence of intrachain ferromagnetic interactions between the S = 3/2 ReIV centers and the 3d metal ions: S = 1 NiII or S = 1/2 CuII. At low temperature, a three-dimensional ordered magnetic phase induced by interchain antiferromagnetic interactions (antiferromagnetic for 1 and 2; canted antiferromagnetic for 3) is detected for the three compounds.
Published: 2012
Full Text: View/download PDF

38. [ReCl4(CN)2]2-: A High Magnetic Anisotropy Building Unit Giving Rise to the Single-Chain Magnets (DMF)4MReCl4(CN)2 (M ) Mn, Fe, Co, Ni)

Author: DAVID HARRIS, T., V. BENNETT, Miriam, CLÉRAC, Rodolphe, R. LONG, Jeffrey, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Department of Chemistry and Biochemistry, San Diego, San Diego State University (SDSU), Centre de recherches Paul Pascal (CRPP), and Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [CHIM.COOR]Chemical Sciences/Coordination chemistry, Single-Chain Magnets, [CHIM.MATE]Chemical Sciences/Material chemistry, Magnetic anisotropy
Abstract: 9 pages; International audience; An S ) 3/2, high-anisotropy building unit, trans-[ReCl4(CN)2]2-, representing the first paramagnetic complex with a mixture of just cyanide and halide ligands, has been synthesized through the reaction of (Bu4N)CN with ReCl4(THF)2. This species is characterized in detail and employed in directing the formation of a series of one-dimensional coordination solids of formula (DMF)4MReCl4(CN)2 (M ) Mn (2), Fe (3), Co (4), Ni (5)). Variable-temperature dc magnetic susceptibility measurements demonstrate the presence of intrachain antiferromagnetic (2) and ferromagnetic (3-5) exchange coupling within these solids. In addition, probing the ac magnetic susceptibility as a function of both temperature and frequency reveals that all of the chain compounds exhibit slow relaxation of the magnetization. The relaxation time is shown to be thermally activated, with energy barriers to relaxation of Δτ ) 31, 56, 17, and 20 cm-1 for 2-5, respectively. Notably, the field-dependent magnetization of the iron congener exhibits a significant hysteresis effect at low temperature, with a coercive field of HC ) 1.0 T, thus demonstrating magnetlike behavior in this onedimensional system. Finally, the magnetization dynamics of all solids occur within the finite-size regime, where the magnetic domain growth is limited due to physical defects along the chains within the crystals.
Published: 2010

39. Multi-step breathing in the Metal-Organic Framework Co(1,4-benzenedipyrazolate)

Author: Salles, Fabrice, Maurin, Guillaume, Serre, C., Llewellyn, P. L., Long, J., Choi, H., Filinchuk, Y., Ferey, Gerard, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2), Institut Lavoisier de Versailles (ILV), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS), Matériaux divisés, interfaces, réactivité, électrochimie (MADIREL), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Institut Laue-Langevin (ILL), and ILL
Subjects: [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2010
Full Text: View/download PDF

40. Hydrogen for X-group exchange in CHX (X = Cl, Br, I , OMe, and NMe) by monomeric [1,2,4-(Me3C)3C5H2]2CeH: experimental and computational support for a carbenoid mechanism

Author: L. Werkema, Evan, A. Andersen, Richard, Yahia, Ahmed, Maron, Laurent, Eisenstein, Odile, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), and Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2009
Full Text: View/download PDF

41. First-order dynamical phase transition in models of glasses: an approach based on ensembles of histories

Author: Vivien Lecomte, Robert L. Jack, Estelle Pitard, Juan P. Garrahan, K. van Duijvendijk, F. van Wijland, School of Physics and Astronomy [Nottingham], University of Nottingham, UK (UON), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Matière et Systèmes Complexes (MSC (UMR_7057)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des colloïdes, verres et nanomatériaux (LCVN), Université Montpellier 2 - Sciences et Techniques (UM2)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)
Subjects: Statistics and Probability, Physics, Phase transition, Statistical Mechanics (cond-mat.stat-mech), FOS: Physical sciences, General Physics and Astronomy, Statistical and Nonlinear Physics, First order, 01 natural sciences, PACS numbers: 05.40.?a, 64.70.Pf, 010305 fluids & plasmas, Modeling and Simulation, Lattice (order), 0103 physical sciences, Statistical physics, [PHYS.COND.CM-SM]Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech], 010306 general physics, Condensed Matter - Statistical Mechanics, Mathematical Physics, Deviation function
Abstract: We investigate the dynamics of kinetically constrained models of glass formers by analysing the statistics of trajectories of the dynamics, or histories, using large deviation function methods. We show that, in general, these models exhibit a first-order dynamical transition between active and inactive dynamical phases. We argue that the dynamical heterogeneities displayed by these systems are a manifestation of dynamical first-order phase coexistence. In particular, we calculate dynamical large deviation functions, both analytically and numerically, for the Fredrickson-Andersen model, the East model, and constrained lattice gas models. We also show how large deviation functions can be obtained from a Landau-like theory for dynamical fluctuations. We discuss possibilities for similar dynamical phase-coexistence behaviour in other systems with heterogeneous dynamics., 29 pages, 7 figs, final version
Published: 2009
Full Text: View/download PDF

42. Stable Noncyclic Singlet Carbenes

Author: Joan Vignolle, Xavier Cattoën, Didier Bourissou, Laboratoire de Chimie des Polymères Organiques (LCPO), Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC), Team 1 LCPO : Polymerization Catalyses & Engineering, Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Ecole Nationale Supérieure de Chimie, de Biologie et de Physique (ENSCBP)-Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC), Laboratoire Hétérochimie Fondamentale et Appliquée (LHFA), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Department of Chemistry [Riverside], University of California [Riverside] (UCR), University of California-University of California, Department of Chemistry [Berkeley], University of California [Berkeley], Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)
Subjects: FREE CATALYTIC-HYDROGENATION, 010405 organic chemistry, Chemistry, [CHIM.ORGA]Chemical Sciences/Organic chemistry, C-H ACTIVATION, BIS(ACYCLIC DIAMINOCARBENE) COMPLEX, DIVALENT CARBON(0) CHEMISTRY, General Chemistry, 010402 general chemistry, 01 natural sciences, TRANSITION-METAL-COMPLEXES, 0104 chemical sciences, DENSITY-FUNCTIONAL THEORY, [CHIM.POLY]Chemical Sciences/Polymers, X-RAY CRYSTAL, N-HETEROCYCLIC CARBENES, MIYAURA COUPLING PROCESSES, Organic chemistry, Density functional theory, Singlet state, ComputingMilieux_MISCELLANEOUS, AMINO PHOSPHORUS YLIDES
Abstract: International audience
Published: 2009
Full Text: View/download PDF

43. Ionization phase-match gating for wavelength-tunable isolated attosecond pulse generation

Author: Thomas Pfeifer, Phillip M. Nagel, Aurélie Jullien, Mark J. Abel, Stephen R. Leone, M. J. Bell, Daniel M. Neumark, Laboratoire d'optique appliquée (LOA), École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Chemical Sciences Division [LBNL Berkeley] (CSD), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, and Department of Physics [Berkeley]
Subjects: Physics, Femtosecond pulse shaping, Leading edge, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], Physics and Astronomy (miscellaneous), business.industry, Attosecond, General Engineering, Physics::Optics, General Physics and Astronomy, Nonlinear optics, Laser, 01 natural sciences, law.invention, Pulse (physics), 010309 optics, Optics, law, PACS 42.65.Ky, 41.50.+h, 42.50.Hz, 42.65.Re, 0103 physical sciences, High harmonic generation, 010306 general physics, business, Ultrashort pulse
Abstract: International audience; High-order harmonic emission can be confined to the leading edge of an 800 nm driver laser pulse under moderately intense focusing conditions (7×10^14 W/cm^2) (Pfeifer et al. in Opt. Express 15:17120, 2007). Here, the experimentally observed curtailment of harmonic production on the leading edge of the driver pulse is shown to be controlled by an ionization-induced phase-matching condition. The transient plasma density inherent to the process of high-harmonic generation terminates the harmonic emission by an ultrafast loss of phase matching on the leading edge of the laser pulse. The analysis is supported by a reconstruction of the in situ intensity envelope of the driver pulse with attosecond temporal resolution, performed by measurements of the carrier-envelope phase dependence of individual half-cycle harmonic cutoffs. The method opens the way to wavelength-tunable isolated attosecond pulse generation.
Published: 2008
Full Text: View/download PDF

44. Determination of the evaporation coefficient of D2O

Author: R. C. Cohen, R. J. Saykally, J. D. Smith, C. D. Cappa, W. S. Drisdell, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Chemical Sciences Division [LBNL Berkeley] (CSD), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Department of Civil and Environmental Engineering [UC Davis], University of California [Davis] (UC Davis), and Department of Earth and Planetary Science [UC Berkeley] (EPS)
Subjects: lcsh:Chemistry, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, lcsh:QD1-999, lcsh:Physics, lcsh:QC1-999
Abstract: International audience; The evaporation rate of D2O has been determined by Raman thermometry of a droplet train (12?15 µm diameter) injected into vacuum (~10-5 torr). The cooling rate measured as a function of time in vacuum was fit to a model that accounts for temperature gradients between the surface and the core of the droplets, yielding an evaporation coefficient (?e) of 0.57±0.06. This is nearly identical to that found for H2O (0.62±0.09) using the same experimental method and model, and indicates the existence of a kinetic barrier to evaporation. The application of a recently developed transition-state theory (TST) model suggests that the kinetic barrier is due to librational and hindered translational motions at the liquid surface, and that the lack of an isotope effect is due to competing energetic and entropic factors. The implications of these results for cloud and aerosol particles in the atmosphere are discussed.
Published: 2008

45. DFT Investigation of the Catalytic Hydromethylation of Olefins by Scandocenes. 2. Influence of the Ansa Ligand on Propene and Isobutene Hydromethylation

Author: Odile Eisenstein, T. Don Tilley, Noémi Barros, Laurent Maron, Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie Séparative de Marcoule (ICSM - UMR 5257), Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)
Subjects: 010405 organic chemistry, Ligand, Chemistry, Organic Chemistry, 010402 general chemistry, Photochemistry, 01 natural sciences, 0104 chemical sciences, Catalysis, Inorganic Chemistry, Propene, chemistry.chemical_compound, Computational chemistry, Density functional theory, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Physical and Theoretical Chemistry, ComputingMilieux_MISCELLANEOUS
Abstract: Density functional theory (B3PW91) calculations have been carried out for the hydromethylation of propene and isobutene catalyzed by ansa-Me2Si(C5Me4)2ScCH, as modeled by H2Si(C5H4)2ScCH3. The calc...
Published: 2008
Full Text: View/download PDF

46. Coherence transfer between spy nuclei and nitrogen-14 in solids

Author: Geoffrey Bodenhausen, Anuji Abraham, Simone Cavadini, Laboratoire de Résonance Magnétique Biomoléculaire, Ecole Polytechnique Fédérale de Lausanne (EPFL), Institut des sciences et d'ingénierie chimiques (ISIC), Université Pierre et Marie Curie - Paris 6 (UPMC), Département de Chimie - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Department of Chemistry [Berkeley], University of California [Berkeley], and University of California-University of California
Subjects: Nuclear and High Energy Physics, Magic angle, Magnetic Resonance Spectroscopy, Nitrogen, Biophysics, Glycine, 010402 general chemistry, 01 natural sciences, Biochemistry, Molecular physics, Nuclear magnetic resonance, Isotopes, Magic angle spinning, Spectroscopy, ComputingMilieux_MISCELLANEOUS, Carbon Isotopes, Alanine, Spins, Nitrogen Isotopes, 010405 organic chemistry, Chemistry, [CHIM.ORGA]Chemical Sciences/Organic chemistry, Spectrum Analysis, Phosphorus Isotopes, Condensed Matter Physics, Deuterium, 0104 chemical sciences, Solid-state nuclear magnetic resonance, Heteronuclear molecule, Heteronuclear single quantum coherence spectroscopy, Coherence (physics)
Abstract: International audience ; Coherence transfer from 'spy nuclei' such as (1)H or (13)C (S=1/2) was used to excite single- or double-quantum coherences of (14)N nuclei (I=1) while the S spins were aligned along the static field, in the manner of heteronuclear single-quantum correlation (HSQC) spectroscopy. For samples spinning at the magic angle, coherence transfer can be achieved through a combination of scalar couplings J(I,S) and second-order quadrupole-dipole cross-terms, also known as residual dipolar splittings (RDS). The second-order quadrupolar powder patterns in the two-dimensional spectra allow one to determine the quadrupolar parameters of (14)N in amino acids.
Published: 2008
Full Text: View/download PDF

47. Generating coherent broadband continuum soft-x-ray radiation by attosecond ionization gating

Author: Thomas Pfeifer, Stephen R. Leone, Phillip M. Nagel, Aurélie Jullien, Daniel M. Neumark, Lukas Gallmann, Mark J. Abel, Chemical Sciences Division [LBNL Berkeley] (CSD), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Department of Physics [Berkeley], University of California [Berkeley], University of California-University of California, and Department of Chemistry [Berkeley]
Subjects: Physics, Femtosecond pulse shaping, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], business.industry, Attosecond, Physics::Optics, 01 natural sciences, Pulse shaping, Atomic and Molecular Physics, and Optics, 010309 optics, Optics, Pulse compression, 0103 physical sciences, Pulse wave, High harmonic generation, Physics::Atomic Physics, 010306 general physics, business, Ultrashort pulse, Bandwidth-limited pulse
Abstract: International audience; The current paradigm of isolated attosecond pulse production requires a few-cycle pulse as the driver for high-harmonic generation that has a cosine-like electric field stabilized with respect to the peak of the pulse envelope. Here, we present simulations and experimental evidence that the production of high-harmonic light can be restricted to one or a few cycles on the leading edge of a laser pulse by a gating mechanism that employs time-dependent ionization of the conversion medium. This scheme enables the generation of broadband and tunable attosecond pulses. Instead of fixing the carrier-envelope phase to produce a cosine driver pulse, the phase becomes a control parameter for the center frequency of the attosecond pulse. A method to assess the multiplicity of attosecond pulses in the pulse train is also presented. The results of our study suggest an avenue towards relaxing the requirement of few-cycle pulses for isolated attosecond pulse generation.
Published: 2007
Full Text: View/download PDF

48. Isolated attosecond pulses using a detuned second-harmonic field

Author: Willem Boutu, Aurélie Jullien, Thomas Pfeifer, Thierry Auguste, Hamed Merdji, Daniel M. Neumark, Bertrand Carré, Stephen R. Leone, J.-Pascal Caumes, Service des Photons, Atomes et Molécules (SPAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Stanford PULSE Center, SLAC National Accelerator Laboratory (SLAC), Stanford University-Stanford University, Chemical Sciences Division [LBNL Berkeley] (CSD), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Department of Physics [Berkeley], University of California [Berkeley], University of California-University of California, Department of Chemistry [Berkeley], University of California [Berkeley] (UC Berkeley), and University of California (UC)-University of California (UC)
Subjects: Physics, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], Field (physics), business.industry, Pulse generator, Wave packet, Attosecond, Nonlinear optics, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010309 optics, Optics, Coherent control, Electric field, 0103 physical sciences, Physics::Atomic Physics, 010306 general physics, business, Ultrashort pulse
Abstract: Calculations are presented for the generation of an isolated attosecond pulse in a multicycle two-color strong-field regime. We show that the recollision of the electron wave packet can be confined to half an optical cycle using pulses of up to 40 fs in duration. The scheme is proven to be efficient using two intense beams, one producing a strong field at {omega} and the other a strong field detuned from 2{omega}. The slight detuning {delta}{omega} of the second harmonic is used to break the symmetry of the electric field over many optical cycles and provides a coherent control for the formation of an isolated attosecond pulse.
Published: 2007
Full Text: View/download PDF

49. VOC reactivity in central California: comparing an air quality model to ground-based measurements

Author: Allison L. Steiner, Gunnar W. Schade, Ronald C. Cohen, Robert A. Harley, Shaheen R. Tonse, Allen H. Goldstein, Dylan B. Millet, Department of Atmospheric, Oceanic, and Space Sciences [Ann Arbor] (AOSS), University of Michigan [Ann Arbor], University of Michigan System-University of Michigan System, Department of Chemistry [Berkeley], University of California [Berkeley], University of California-University of California, Department of Earth and Planetary Science [UC Berkeley] (EPS), Department of Civil and Environmental Engineering [Berkeley] (CEE), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Department of Environmental Science, Policy and Management, Department of Earth and Planetary Sciences [Cambridge, USA] (EPS), Harvard University [Cambridge], Department of Atmospheric Sciences [College Station], Texas A&M University [College Station], Department of Chemistry, and University of California
Subjects: chemistry.chemical_classification, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, Formaldehyde, lcsh:QC1-999, lcsh:Chemistry, chemistry.chemical_compound, lcsh:QD1-999, chemistry, Environmental chemistry, Volatile organic compound, Reactivity (chemistry), Air quality index, lcsh:Physics, Oxygenate, CMAQ
Abstract: Volatile organic compound (VOC) reactivity in central California is examined using a photochemical air quality model (the Community Multiscale Air Quality model; CMAQ) and ground-based measurements to evaluate the contribution of VOC to photochemical activity. We classify VOC into four categories: anthropogenic, biogenic, aldehyde, and other oxygenated VOC. Anthropogenic and biogenic VOC consist of primary emissions, while aldehydes and other oxygenated VOC include both primary anthropogenic emissions and secondary products from primary VOC oxidation. To evaluate the model treatment of VOC chemistry, we compare calculated and modeled OH and VOC reactivities using the following metrics: 1) cumulative distribution functions of NOx concentration and VOC reactivity (ROH,VOC), 2) the relationship between ROH,VOC and NOx, 3) total OH reactivity (ROH,total) and speciated contributions, and 4) the relationship between speciated ROH,VOC and NOx. We find that the model predicts ROH,total to within 25–40% at three sites representing urban (Sacramento), suburban (Granite Bay) and rural (Blodgett Forest) chemistry. However in the urban area of Fresno, the model under predicts NOx and VOC emissions by a factor of 2–3. At all locations the model is consistent with observations of the relative contributions of total VOC. In urban areas, anthropogenic and biogenic ROH,VOC are predicted fairly well over a range of NOx conditions. In suburban and rural locations, anthropogenic and other oxygenated ROH,VOC relationships are reproduced, but calculated biogenic and aldehyde ROH,VOC are often poorly characterized by measurements, making evaluation of the model with available data unreliable. In central California, 30–50% of the modeled urban VOC reactivity is due to aldehydes and other oxygenated species, and the total oxygenated ROH,VOC is nearly equivalent to anthropogenic VOC reactivity. In rural vegetated regions, biogenic and aldehyde reactivity dominates. This indicates that more attention needs to be paid to the accuracy of models and measurements of both primary emissions of oxygenated VOC and secondary production of oxygenates, especially formaldehyde and other aldehydes, and that a more comprehensive set of oxygenated VOC measurements is required to include all of the important contributions to atmospheric reactivity.
Published: 2007

50. Reactions of Monomeric [1,2,4 (Me3C)3C5H2]2CeH and CO with or without H2: An Experimental and Computational Study

Author: Evan L. Werkema, Richard A. Andersen, Laurent Maron, Odile Eisenstein, Department of Chemistry [Berkeley], University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM ICMMM), Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), PICS 3422 Université Berkeley, University of California [Berkeley], University of California-University of California, Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), and Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Université Montpellier 2 - Sciences et Techniques (UM2)-Institut de Chimie du CNRS (INC)
Subjects: 010405 organic chemistry, Stereochemistry, Formaldehyde, General Chemistry, 010402 general chemistry, 01 natural sciences, Biochemistry, Toluene, Medicinal chemistry, Catalysis, 0104 chemical sciences, Solvent, Pentane, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, chemistry.chemical_compound, Colloid and Surface Chemistry, Monomer, chemistry, Chemical Sciences, Lone pair, Carbene, Metallocene
Abstract: Addition of CO to [1,2,4-(Me3C)3C5H2]2CeH, Cp'2CeH, in toluene yields the cis (Cp'2Ce)2(mu-OCHCHO), in which the cis enediolate group bridges the two metallocene fragments. The cis enediolate quantitatively isomerizes intramolecularly to the trans-enediolate in C6D6 at 100oC over seven months. When the solvent is pentane, Cp'2Ce(OCH2)CeCp'2 forms, in which the oxomethylene group or the formaldehyde dianion bridges the two metallocene fragments. The cis enediolate is suggested to form by insertion of CO into the Ce-C bond of Cp'2Ce(OCH2)CeCp'2 generating Cp'2CeOCH2COCeCp'2. The stereochemistry of the cis-enediolate is determined by a 1,2-hydrogen shift in the OCH2CO fragment that has the OC(H2) bond anti periplanar relative to the carbene lone pair. The bridging oxomethylene complex reacts with H2, but not with CH4, to give Cp'2CeOMe, which is also the product of the reaction between Cp'2CeH and a mixture of CO and H2. The oxomethylene complex reacts with CO to give the cis enediolate complex. DFT calculations on C5H5 model metallocenes show that the reaction of Cp2CeH with CO and H2 to give Cp2CeOMe is exoergic by 50 kcal mol-1. The net reaction proceeds by a series of elementary reactions that occur after the formyl complex, Cp2Ce(eta-2 CHO), is formed by further reaction with H2. The key point that emerges from the calculated potential energy surface is the bifunctional nature of the metal formyl in which the carbon atom behaves as a donor and acceptor. Replacing H2 by CH4 increases the activation energy barrier by 17 kcal mol-1.
Published: 2007
Full Text: View/download PDF

Catalog

Books, media, physical & digital resources

See catalog results

Searchworks

Select search scope, currently: Articles Catalog books, media & more in Jio Institute collections Articles journal articles & other e-resources

Search

Search Constraints

Refine your results

Search Limiters

Topic

Publication Year Range

Publication Type

Journal

Database

Publisher

83 results on '"Department of Chemistry [Berkeley]"'

Search Results

Catalog

Select search scope, currently: Articles

Catalog

books, media & more in Jio Institute collections

Articles

journal articles & other e-resources