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1. Catalytic Nitrene Transfer by an Fe IV ‐Imido Complex Generated by a Comproportionation Process

Author

Jordan Donat, Patrick Dubourdeaux, Martin Clémancey, Julia Rendon, Clara Gervasoni, Morgan Barbier, Jessica Barilone, Jacques Pécaut, Serge Gambarelli, Pascale Maldivi, Jean‐Marc Latour, Physiochimie des Métaux (PMB), Laboratoire de Chimie et Biologie des Métaux (LCBM - UMR 5249), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Conception d’Architectures Moléculaires et Processus Electroniques (CAMPE ), SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SYMMES), Institut des Sciences Moléculaires (ISM), Université Montesquieu - Bordeaux 4-Université Sciences et Technologies - Bordeaux 1 (UB)-École Nationale Supérieure de Chimie et de Physique de Bordeaux (ENSCPB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Chimie Interface Biologie pour l’Environnement, la Santé et la Toxicologie (CIBEST ), and ANR-17-EURE-0003,CBH-EUR-GS,CBH-EUR-GS(2017)

Subjects
[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, spectroscopy, iron, nitrene transfer, density functional calculations, tetracarbene macrocycles, Organic Chemistry, [CHIM.COOR]Chemical Sciences/Coordination chemistry, [INFO]Computer Science [cs], [CHIM.CATA]Chemical Sciences/Catalysis, General Chemistry, Catalysis
Abstract

International audience; Nitrene transfer reactions have emerged as one of the most powerful and versatile ways to insert an amine function to various kinds of hydrocarbon substrates. However, the mechanisms of nitrene generation have not been studied in depth albeit their formation is taken for granted in most cases without definitive evidence of their occurrence. In the present work, we compare the generation of tosylimido iron species and NTs transfer from Fe-II and Fe-III precursors where the metal is embedded in a tetracarbene macrocycle. Catalytic nitrene transfer to reference substrates (thioanisole, styrene, ethylbenzene and cyclohexane) revealed that the same active species was at play, irrespective of the ferrous versus ferric nature of the precursor. Through combination of spectroscopic (UV-visible, Mossbauer), ESI-MS and DFT studies, an Fe-IV tosylimido species was identified as the catalytically active species and was characterized spectroscopically and computationally. Whereas its formation from the Fe-II precursor was expected by a two-electron oxidative addition, its formation from an Fe-III precursor was unprecedented. Thanks to a combination of spectroscopic (UV-visible, EPR, Hyscore and Mossbauer), ESI-MS and DFT studies, we found that, when starting from the Fe-III precursor, an Fe-III tosyliodinane adduct was formed and decomposed into an Fe-V tosylimido species which generated the catalytically active Fe-IV tosylimide through a comproportionation process with the Fe-III precursor.

Published
2022
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2. Non‐Covalent Integration of a [FeFe]‐Hydrogenase Mimic to Multiwalled Carbon Nanotubes for Electrocatalytic Hydrogen Evolution

Author

Afridi Zamader, Bertrand Reuillard, Jacques Pécaut, Laurent Billon, Antoine Bousquet, Gustav Berggren, Vincent Artero, Solar fuels, hydrogen and catalysis (SolHyCat), Laboratoire de Chimie et Biologie des Métaux (LCBM - UMR 5249), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SYMMES), Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux (IPREM), Université de Pau et des Pays de l'Adour (UPPA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Uppsala University, ANR-11-LABX-0003,ARCANE,Grenoble, une chimie bio-motivée(2011), and ANR-17-EURE-0003,CBH-EUR-GS,CBH-EUR-GS(2017)

Subjects
molecular electrocatalysis, carbon nanotubes, hydrogenase mimic, Chemical Sciences, Organic Chemistry, [CHIM]Chemical Sciences, Kemi, General Chemistry, pyrene, Catalysis, hydrogen evolution reaction
Abstract

International audience; Surface integration of molecular catalysts inspired from the active sites of hydrogenase enzymes represents a promising route towards developing noble metal-free and sustainable technologies for H2 production. Efficient and stable catalyst anchoring is a key aspect to enable this approach. Herein, we report the preparation and electrochemical characterization of an original diironhexacarbonyl complex including two pyrene groups per catalytic unit in order to allow for its smooth integration, through π-interactions, onto multiwalled carbon nanotube-based electrodes. In this configuration, the grafted catalyst could reach turnover numbers for H2 production (TONH2) of up to 4±2×103 within 20 h of bulk electrolysis, operating at neutral pH. Post operando analysis of catalyst functionalized electrodes revealed the degradation of the catalytic unit occurred via loss of the iron carbonyl units, while the anchoring groups and most part of the ligand remained attached onto multiwalled carbon nanotubes.

Published
2022
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3. Cation‐Mediated Conversion of the State of Charge in Uranium Arene Inverted‐Sandwich Complexes

Author

Clément Camp, Jacques Pécaut, Victor Mougel, Laurent Maron, Marinella Mazzanti, Reconnaissance Ionique et Chimie de Coordination (RICC), SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SYMMES), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), 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), Service de Chimie Inorganique et Biologique (SCIB - UMR E3), Institut Nanosciences et Cryogénie (INAC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Centre National de la Recherche Scientifique (CNRS), ANR-10-BLAN-0729,NUMA,Nouvelles architectures moléculaires et supramoléculaires basée sur l'U(V).(2010), Institut de Chimie du CNRS (INC)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), 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), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010405 organic chemistry, Stereochemistry, Organic Chemistry, Siloxide, Disproportionation, General Chemistry, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, Toluene, Redox, Catalysis, 0104 chemical sciences, chemistry.chemical_compound, chemistry, [CHIM]Chemical Sciences, Reactivity (chemistry), Trifluoromethanesulfonate, Stoichiometry, Group 2 organometallic chemistry
Abstract

Two new arene inverted-sandwich complexes of uranium supported by siloxide ancillary ligands [K{U(OSi(OtBu)3)3}2(μ-η(6):η(6)-C7H8)] (3) and [K2{U(OSi(OtBu)3)3}2(μ-η(6):η(6)-C7H8)] (4) were synthesized by the reduction of the parent arene-bridged complex [{U(OSi(OtBu)3)3}2(μ-η(6):η(6)-C7H8)] (2) with stoichiometric amounts of KC8 yielding a rare family of inverted-sandwich complexes in three states of charge. The structural data and computational studies of the electronic structure are in agreement with the presence of high-valent uranium centers bridged by a reduced tetra-anionic toluene with the best formulation being U(V)-(arene(4-))-U(V), KU(IV)-(arene(4-))-U(V), and K2U(IV)-(arene(4-))-U(IV) for complexes 2, 3, and 4 respectively. The potassium cations in complexes 3 and 4 are coordinated to the siloxide ligands both in the solid state and in solution. The addition of KOTf (OTf=triflate) to the neutral compound 2 promotes its disproportionation to yield complexes 3 and 4 (depending on the stoichiometry) and the U(IV) mononuclear complex [U(OSi(OtBu)3)3(OTf)(thf)2] (5). This unprecedented reactivity demonstrates the key role of potassium for the stability of these complexes.

Published
2013
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4. 1,2-Dihydrotriazinyl-N-oxy Free Radicals

Author

Peter Brough, Serge Gambarelli, Paul Rey, Jean-François Jacquot, André Grand, and Jacques Pécaut

Subjects
Nitroxide mediated radical polymerization, Chemistry, Radical, Organic Chemistry, General Chemistry, Ring (chemistry), Photochemistry, Catalysis, law.invention, Delocalized electron, Crystallography, Unpaired electron, law, X-ray crystallography, Electron paramagnetic resonance, Hyperfine structure
Abstract

Triazinyl-N-oxy free radicals, 2-methyl-2,4,6-triphenyl-1,2-dihydro-1,3,5-triazinyl-1-oxy (6a), 2,2,4,6-tetraphenyl-1,2-dihydro-1,3,5-triazinyl-1-oxy (6b), 2,2-dimethyl-4,6-diphenyl-1,2-dihydro-1,3,5-triazinyl-1-oxy (13), and 2,6-dimethyl-2,4-diphenyl-1,2-dihydro-1,3,5-triazinyl-1-oxy (14), in which the unpaired electron is delocalized over three nitrogen atoms, have been prepared and characterized. A method has been devised for introducing an N-oxide function into the triazinyl core. Then, by using a Grignard reagent, substitution α to the N-oxide group was achieved and the resulting 1,2-dihydrotriazine-N-oxide oxidized into the corresponding nitroxide. Solution EPR spectra exhibit hyperfine splitting that confirms spin delocalization over the three nitrogen atoms of the triazinyl ring. They also show that spin delocalization diminishes with increasing distance for the coupling and is largest for nitrogen N1 and weakest for N5. Free radicals 6a and 13 are stable in the solid state and have been characterized by X-ray diffraction, but they tend to gradually degrade in solution. In the solid state, these two free radicals are arranged into antiferromagnetically exchange-coupled pairs, J=-5.2(6) for 6a and -3.7(4) cm(-1) for 13 (H=-2JS(1)S(2)).

Published
2011
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5. Remarkable Tuning of the Coordination and Photophysical Properties of Lanthanide Ions in a Series of Tetrazole-Based Complexes

Author

Jacques Pécaut, Eugen S. Andreiadis, Marinella Mazzanti, Daniel Imbert, Renaud Demadrille, SYstèmes Moléculaires et nanoMatériaux pour l’Energie et la Santé (SYMMES), Institut de Chimie du CNRS (INC)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Dynamique des écosystèmes Caraïbe et biologie des espèces associées (DYNECAR EA 926), Université des Antilles et de la Guyane (UAG), Institut des Sciences et Ingénierie Chimiques (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), and Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)

Subjects
Lanthanide, Luminescence, Inorganic chemistry, Molecular Conformation, Tetrazoles, Crystallography, X-Ray, Ligands, 010402 general chemistry, Lanthanoid Series Elements, 01 natural sciences, Catalysis, Coordination complex, chemistry.chemical_compound, Bipyridine, [CHIM]Chemical Sciences, Tetrazole, Carboxylate, Homoleptic, ComputingMilieux_MISCELLANEOUS, chemistry.chemical_classification, [CHIM.ORGA]Chemical Sciences/Organic chemistry, 010405 organic chemistry, Ligand, Organic Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, General Chemistry, Photochemical Processes, 0104 chemical sciences, Crystallography, chemistry, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Quantum Theory, Terpyridine
Abstract

A series of seven new tetrazole-based ligands (L1, L3-L8) containing terpyridine or bipyridine chromophores suited to the formation of luminescent complexes of lanthanides have been synthesized. All ligands were prepared from the respective carbonitriles by thermal cycloaddition of sodium azide. The crystal structures of the homoleptic terpyridine-tetrazolate complexes [Ln(Li)(2)]NHEt(3) (Ln = Nd, Eu, Tb for i = 1, 2; Ln = Eu for i = 3, 4) and of the monoaquo bypyridine-tetrazolate complex [Eu(H(2)O)(L7)(2)]NHEt(3) were determined. The tetradentate bipyridine-tetrazolate ligand forms nonhelical complexes that can contain a water molecule coordinated to the metal. Conversely, the pentadentate terpyridine-tetrazolate ligands wrap around the metal, thereby preventing solvent coordination and forming chiral double-helical complexes similarly to the analogue terpyridine-carboxylate. Proton NMR spectroscopy studies show that the solid-state structures of these complexes are retained in solution and indicate the kinetic stability of the hydrophobic complexes of terpyridine-tetrazolates. UV spectroscopy results suggest that terpyridine-tetrazolate complexes have a similar stability to their carboxylate analogues, which is sufficient for their isolation in aerobic conditions. The replacement of the carboxylate group with tetrazolate extends the absorption window of the corresponding terpyridine- (approximately 20 nm) and bipyridine-based (25 nm) complexes towards the visible region (up to 440 nm). Moreover, the substitution of the terpyridine-tetrazolate system with different groups in the ligand series L3-L6 has a very important effect on both absorption spectra and luminescence efficiency of their lanthanide complexes. The tetrazole-based ligands L1 and L3-L8 sensitize efficiently the luminescent emission of lanthanide ions in the visible and near-IR regions with quantum yields ranging from 5 to 53% for Eu(III) complexes, 6 to 35% for Tb(III) complexes, and 0.1 to 0.3% for Nd(III) complexes, which is among the highest reported for a neodymium complex. The luminescence efficiency could be related to the energy of the ligand triplet states, which are strongly correlated to the ligand structures.

Published
2009
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6. Cyclopentadienyl Ruthenium–Nickel Catalysts for Biomimetic Hydrogen Evolution: Electrocatalytic Properties and Mechanistic DFT Studies

Author

Marc Fontecave, Sigolène Canaguier, Jacques Pécaut, Loredana Vaccaro, Rainer Ostermann, Vincent Artero, Martin J. Field, Laboratoire de Chimie et Biologie des Métaux (LCBM - UMR 5249), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut de biologie structurale (IBS - UMR 5075 ), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Service de Chimie Inorganique et Biologique (SCIB - UMR E3), Institut Nanosciences et Cryogénie (INAC), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Centre National de la Recherche Scientifique (CNRS), Collège de France - Chaire Chimie des processus biologiques, Laboratoire de Chimie des Processus Biologiques (LCPB), Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), and Chaire Chimie des processus biologiques

Subjects
Molecular Conformation, chemistry.chemical_element, Cyclopentanes, Crystallography, X-Ray, 010402 general chemistry, Photochemistry, 01 natural sciences, Catalysis, hydrogenases, nickel, bioinspired chemistry, Hydrogenase, Cyclopentadienyl complex, Catalytic Domain, [CHIM]Chemical Sciences, ruthenium, [PHYS]Physics [physics], 010405 organic chemistry, Hydride, Chemistry, Organic Chemistry, [CHIM.CATA]Chemical Sciences/Catalysis, General Chemistry, 0104 chemical sciences, Ruthenium, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Nickel, Crystallography, Catalytic cycle, Density functional theory, Isomerization, Hydrogen
Abstract

The new dinuclear nickel-ruthenium complexes [Ni(xbsms)RuCp(L)][PF(6)] (H(2)xbsms = 1,2-bis(4-mercapto-3,3-dimethyl-2-thiabutyl)benzene; Cp(-) = cyclopentadienyl; L = DMSO, CO, PPh(3), and PCy(3)) are reported and are bioinspired mimics of NiFe hydrogenases. These compounds were characterized by X-ray diffraction techniques and display novel structural motifs. Interestingly, [Ni(xbsms)RuCpCO][PF(6)] is stereochemically nonrigid in solution and an isomerization mechanism was derived with the help of density functional theory (DFT) calculations. Because of an increased electron density on the metal centers [Eur. J. Inorg. Chem. 2007, 18, 2613-2626] with respect to the previously described [Ni(xbsms)Ru(CO)(2)Cl(2)] and [Ni(xbsms)Ru(p-cymene)Cl](+) complexes, [Ni(xbsms)RuCp(dmso)][PF(6)] catalyzes hydrogen evolution from Et(3)NH(+) in DMF with an overpotential reduced by 180 mV and thus represents the most efficient NiFe hydrogenase functional mimic. DFT calculations were carried out with several methods to investigate the catalytic cycle and, coupled with electrochemical measurements, allowed a mechanism to be proposed. A terminal or bridging hydride derivative was identified as the active intermediate, with the structure of the bridging form similar to that of the Ni-C active state of NiFe hydrogenases.

Published
2009
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7. Definition of Magneto-Structural Correlations for the MnIIIon

Author

Jacques Pécaut, Frank Neese, Marie-Noëlle Collomb, Carole Duboc, and Alain Deronzier

Subjects
Coordination sphere, Ligand, Coordination number, Organic Chemistry, General Chemistry, Zero field splitting, Catalysis, law.invention, chemistry.chemical_compound, Crystallography, Deprotonation, chemistry, Octahedron, Computational chemistry, law, Terpyridine, Electron paramagnetic resonance
Abstract

The electronic properties of the high spin mononuclear Mn II complexes [Mn(tpa)(NCS) 2 ] (1) (tpa=tris-2-picolylamine), [Mn(tBu 3 -terpy) 2 ]-(PF 6 ) 2 (2) (tBu 3 -terpy=4,4',4"-tri-tert-butyl-2,2':6',2"-terpyridine) and [Mn-(terpy) 2 ](I) 2 (3) (terpy =2,2':6',2"-terpyridine) with an N6 coordination sphere have been determined by multifrequency EPR spectroscopy. The X-ray structures of 1-CH 3 CN and 2.C 4 H 10 O.0.5 C 2 H 5 OH.0.5 CH 3 OH reveal that the Mn ll ion lies at the center of a distorted octahedron. The D-values of 1-3 all fall in the narrow range of 0.041 to 0.105 cm -1 . The comparison of the results reported here and those found in the literature is consistent with the following observation: the D value is sensitive to the coordination number (6 or 5) of the Mn ll ion as long as the coordination sphere involves only nitrogen and/or oxygen based ligands. This magneto-structural correlation has been analyzed in this work though DFT model calculations. The zero-field splitting (zfs) parameters of 1-3 have been calculated and are in reasonable agreement with the experimental values. Hypothetical simplified models [Mn(NH 3 ) x (OH 2 ) y ] 2+ (x+y=5 or 6 and [Mn(NH 3 ) 5 X] + (X=OH, Cl)) have been constructed to investigate the origin of the zfs. This investigation reveals i) that D is sensitive to the coordination number (5 or 6) of the Mn ll ion, ii) for the five coordinate systems the major contribution to D is the spin-orbit coupling part, iii) for the six coordinate systems the major contribution to D is the spin-spin interaction and iv) the deprotonation of a water ligand leads to an increase of D, consistent with the relative ligand fields of OH versus H 2 O.

Published
2008
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8. Cover Picture: An Experimental and Theoretical Investigation on Pentacoordinated Cobalt(III) Complexes with an Intermediate S= 1 Spin State: How Halide Ligands Affect their Magnetic Anisotropy (Chem. Eur. J. 3/2016)

Author

Marcello Gennari, Maylis Orio, Mathieu Rouzières, Carole Duboc, Deborah Brazzolotto, Rodolphe Clérac, Shengying Yu, and Jacques Pécaut

Subjects
Magnetic anisotropy, Spin states, Computational chemistry, Chemistry, Organic Chemistry, Physical chemistry, Halide, chemistry.chemical_element, Cover (algebra), General Chemistry, Quantum chemistry, Cobalt, Catalysis
Published
2016
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9. Inside Cover: Lanthanide(II) Complexes Supported by N,O‐Donor Tripodal Ligands: Synthesis, Structure, and Ligand‐Dependent Redox Behavior (Chem. Eur. J. 43/2015)

Author

Gülay Bozoklu, Marinella Mazzanti, Lionel Dubois, Julie Andrez, Rosario Scopelliti, Jacques Pécaut, and Grégory Nocton

Subjects
Lanthanide, chemistry, Ligand, Organic Chemistry, Polymer chemistry, chemistry.chemical_element, General Chemistry, Photochemistry, Europium, Redox, Catalysis
Published
2015
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