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1. A Terminal Yttrium Phosphinidene

Author

Rieser, Theresa E., primary, Wetzel, Philipp, additional, Maichle-Mössmer, Cäcilia, additional, Sirsch, Peter, additional, and Anwander, Reiner, additional

Published
2023
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2. On the Nature of the Bonding in Metal-Silane sigma-Complexes

Author

McGrady, G. Sean, Sirsch, Peter, Chatterton, Nicholas P., Ostermann, Andreas, Gatti, Carlo, Altmannshofer, Sandra, Herz, Verena, Eickerling, Georg, and Scherer, Wolfgang

Subjects
Physics - Chemical Physics
Abstract

The nature of metal silane sigma-bond interaction has been investigated in several key systems by a range of experimental and computational techniques. The structure of [Cp'Mn(CO)2(eta2-HSiHPh2)] 1 has been determined by single crystal neutron diffraction, and the geometry at the Si atom is shown to approximate to a trigonal bipyramid. This complex is similar to [Cp'Mn(CO)2(eta2-HSiFPh2)] 2, whose structure and bonding characteristics have recently been determined by charge density studies based on high-resolution X-ray and neutron diffraction data. The geometry at the Si atom in these sigma-bond complexes is compared with that in other systems containing hypercoordinate silicon. The Mn-H distances for 1 and 2 in solution have been estimated using NMR T1 relaxation measurements, giving a value of 1.56(3) AA in each case, in excellent agreement with the distances deduced from neutron diffraction. DFT calculations have been employed to explore the bonding in the Mn-H-Si unit in 1 and 2 and in the related system [Cp'Mn(CO)2(eta2-HSiCl3)] 3. These studies support the idea that the oxidative addition of a silane ligand to a transition metal center may be described as an asymmetric process in which the Mn-H bond is formed at an early stage, while both the establishment of the Mn-Si bond and also the activation of the eta2-coordinated Si-H moiety are controlled by the extent of Mn-> sigma*(X-Si-H) back-donation, which increases with increasing electronwithdrawing character of the X substituent trans to the metal-coordinated Si-H bond. This delocalized molecular orbital (MO) approach is complemented and supported by combined experimental and theoretical charge density studies including the source function S(r,Omega)., Comment: 39 pages, 7 figures, 4 tables

Published
2008

6. Schlenk's Legacy—Methyllithium Put under Close Scrutiny.

Author

Lebon, Jakob, Mortis, Alexandros, Maichle‐Mössmer, Cäcilia, Manßen, Manfred, Sirsch, Peter, and Anwander, Reiner

Subjects
ORGANOLITHIUM compounds, ORGANIC chemistry, ORGANOMETALLIC chemistry, NUCLEAR magnetic resonance spectroscopy, SALTS, LITHIUM chloride
Abstract

Commercially available stock solutions of organolithium reagents are well‐implemented tools in organic and organometallic chemistry. However, such solutions are inherently contaminated with lithium halide salts, which can complicate certain synthesis protocols and purification processes. Here, we report the isolation of chloride‐free methyllithium employing K[N(SiMe3)2] as a halide‐trapping reagent. The influence of distinct LiCl contaminations on the 7Li‐NMR chemical shift is examined and their quantification demonstrated. The structural parameters of new chloride‐free monomeric methyllithium complex [(Me3TACN)LiCH3], ligated by an azacrown ether, are assessed by comparison with a halide‐contaminated variant and monomeric lithium chloride [(Me3TACN)LiCl], further emphasizing the effect of halide impurities. [ABSTRACT FROM AUTHOR]

Published
2023
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7. Schlenks Vermächtnis – Methyllithium unter der Lupe.

Author

Lebon, Jakob, Mortis, Alexandros, Maichle‐Mössmer, Cäcilia, Manßen, Manfred, Sirsch, Peter, and Anwander, Reiner

Subjects
LITHIUM chloride
Abstract

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2023
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8. Open-Shell Early Lanthanide Terminal Imides

Author

Rieser, Theresa E., primary, Thim-Spöring, Renita, additional, Schädle, Dorothea, additional, Sirsch, Peter, additional, Litlabø, Rannveig, additional, Törnroos, Karl W., additional, Maichle-Mössmer, Cäcilia, additional, and Anwander, Reiner, additional

Published
2022
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11. Galliummethylen

Author

Bonath, Martin, primary, Maichle‐Mössmer, Cäcilia, additional, Sirsch, Peter, additional, and Anwander, Reiner, additional

Published
2019
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12. Gallium Methylene

Author

Bonath, Martin, primary, Maichle‐Mössmer, Cäcilia, additional, Sirsch, Peter, additional, and Anwander, Reiner, additional

Published
2019
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14. [(Triphos)Ni(eta(super 2)-BH4)]: An unusual nickel(I) borohydride complex

Author

Kandiah, Mathivathai, McGrady, G. Sean, Decken, Andreas, and Sirsch, Peter

Subjects
Nickel compounds -- Chemical properties, Chemistry
Abstract

Reduction of [(triphos)NiCI2] with an excess of NaBH4 in THF produces the paramagnetic Ni(I) complex [(triphos)Ni(eta(super 2)-BH4)]. X-ray crystallography shows [(triphos)NiCI2] to be a square-planar Ni(II) species in which the phosphine ligand is bidentate, whereas [(triphos)Ni(eta(super 2)-BH4)] has pseudotetrahedral geometry at the Ni(I) center, with a tridentate phosphine and the borohydride ligand occupying a single coordination site.

Published
2005

19. Insights into metal borohydride and aluminohydride bonding: x-ray and neutron diffraction structures and a DFT and charge density study of [Na(15-crown-5)][E[H.sub.4]] (E = B, Al)

Author

Sirsch, Peter, Clark, Natascha L. N., Onu, Lenua, Burchell, Richard P. L., Decken, Andreas, McGrady, G. Sean, Daoud-Aladine, Aziz, and Gutmann, Matthias J.

Subjects
Sodium compounds -- Chemical properties, Sodium compounds -- Structure, Density functionals -- Usage, Electrostatic interactions -- Analysis, Hydrogen bonding -- Analysis, Neutrons -- Diffraction, Neutrons -- Usage, X-rays -- Diffraction, X-rays -- Usage, Chemistry
Published
2010

20. Nature of the bonding in metal-silane ?-complexes

Author

McGrady, G. Sean, Sirsch, Peter, Chatterton, Nicholas P., Ostermann, Andreas, Gatti, Carlo, Altmannshofer, Sandra, Herz, Verena, Eickerling, Georg, and Scherer, Wolfgang

Subjects
Silane -- Properties, Silane -- Structure, Silane -- Research, Chemical bonds -- Research, X-rays -- Diffraction, X-rays -- Usage, Chemistry
Published
2009

21. Yttrium calix[4]arene complexes. Silylation and silylamine elimination reactions on model oxo surfaces

Author

Anwander, Reiner, Eppinger, Jorg, Nagl, Iris, Scherer, Wolfgang, Tafipolsky, Maxim, and Sirsch, Peter

Subjects
Chemical compounds -- Chemical properties, Chemical compounds -- Research, Calixarenes -- Research, Chemistry
Abstract

The synthesis and the spectroscopic and structural characterization of lower-rim-silylated and rare-earth-metalated calix[4]arenes are described. Depending on the steric bulk of their silyl groups, disilazane reagents HN(SiMe3)(sub 2) and HN(SiMe2)(sub 2) selectively yield bis- and tetrakis-silylated calix[4]arene derivatives and yttrium silylamide Y[N(SiHMe2)(sub 2)](sub 3)(THF)(sub 2) forms aryloxide bond-linked and silylated moieties on the lower-rim calix[4]arene surface

Published
2000

22. Synthesis and structural diversity of trivalent rare-earth metal diisopropylamide complexes

Author

Spallek, Tatiana, primary, Heß, Oliver, additional, Meermann-Zimmermann, Melanie, additional, Meermann, Christian, additional, Klimpel, Michael G., additional, Estler, Frank, additional, Schneider, David, additional, Scherer, Wolfgang, additional, Tafipolsky, Maxim, additional, Törnroos, Karl W., additional, Maichle-Mössmer, Cäcilia, additional, Sirsch, Peter, additional, and Anwander, Reiner, additional

Published
2016
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24. Nature of the bonding in metal-silane σ-complexes

Author

McGrady, G. Sean, Sirsch, Peter, Chatterton, Nicholas P., Ostermann, Andreas, Gatti, Carlo Gatti, Altmannshofer, Sandra, Herz, Verena, Eickerling,Georg, and Scherer, Wolfgang

Subjects
Models, Molecular, Silicon, Neutron diffraction, chemistry.chemical_element, Source Function, 010402 general chemistry, 01 natural sciences, Inorganic Chemistry, chemistry.chemical_compound, Coordination Complexes, Atom, ddc:530, Physical and Theoretical Chemistry, Bonding, Metal-silane complexes, Molecular Structure, 010405 organic chemistry, Spin–lattice relaxation, Charge density, Silanes, Silane, 0104 chemical sciences, Crystallography, Trigonal bipyramidal molecular geometry, Neutron Diffraction, X-ray charge Density, chemistry, Single crystal
Abstract

The nature of metal silane σ-bond interaction has been investigated in several key systems by a range of experimental and computational techniques. The structure of [Cp′Mn(CO)2(η2-HSiHPh2)] 1 has been determined by single crystal neutron diffraction, and the geometry at the Si atom is shown to approximate a trigonal bipyramid; salient bond distances and angles are Mn−H(1) 1.575(14), Si−H(1) 1.806(14), Si−H(2) 1.501(13) Å, and H(1)−Si−H(2) 148.5(8)°. This complex is similar to [Cp′Mn(CO)2(η2-HSiFPh2)] 2, whose structure and bonding characteristics have recently been determined by charge density studies based on high-resolution X-ray and neutron diffraction data. The geometry at the Si atom in these σ-bond complexes is compared with that in other systems containing hypercoordinate silicon. The Mn−H distances for 1 and 2 in solution have been estimated using NMR T1 relaxation measurements, giving a value of 1.56(3) Å in each case, in excellent agreement with the distances deduced from neutron diffraction. Density functional theory calculations have been employed to explore the bonding in the Mn−H−Si unit in 1 and 2 and in the related system [Cp′Mn(CO)2(η2-HSiCl3)] 3. These studies support the idea that the oxidative addition of a silane ligand to a transition metal center may be described as an asymmetric process in which the Mn−H bond is formed at an early stage, while both the establishment of the Mn−Si bond and also the activation of the η2-coordinated Si−H moiety are controlled by the extent of Mn → σ*(X−Si−H) back-donation, which increases with increasing electron-withdrawing character of the X substituent trans to the metal-coordinated Si−H bond. This delocalized molecular orbital (MO) approach is complemented and supported by combined experimental and theoretical charge density studies: the source function S(r,Ω), which provides a measure of the relative importance of each atom’s contribution to the density at a specific reference point r, clearly shows that all three atoms of the Mn(η2-SiH) moiety contribute to a very similar extent to the density at the Mn−Si bond critical point, in pleasing agreement with the MO model. Hence, we advance a consistent and unifying concept which accounts for the degree of Si−H activation in these silane σ-bond complexes.

Published
2009

25. The nature of agostic interactions in complexes of lithium and early transition metals

Author

Sirsch, Peter

Subjects
Lithiumkomplexe, Delokalisierung, Metallorganische Chemie, Übergangsmetallkomplexe, ddc:540, Agostische Wechselwirkung, Elektronendichtebestimmung
Abstract

Die in der metallorganischen Komplexchemie als agostisch bekannten Wechselwirkungen zwischen einem Zentralmetall und der C-H-Bindung eines Liganden besitzen große Relevanz für das Verständnis wichtiger Prozesse, wie z. B. der C-H-Aktivierung sowie der Ziegler-Natta-Katalyse, sind aber dennoch bis heute theoretisch nur unzureichend verstanden. Im Rahmen der Dissertation wurden daher die experimentellen und theoretischen Elektronendichten einer Reihe von agostischen Alkylkomplexen des Lithiums und der frühen Übergangsmetalle bestimmt und mit Hilfe des "Atoms in Molecules"-Ansatzes von Bader bezüglich ihrer Topologie analysiert. Dabei ergab sich, daß in beiden Verbindungsklassen nicht direkte M...H-C-Wechselwirkungen die entscheidende Rolle spielen und zu den beobachteten, strukturellen Verzerrungen führen, sondern stattdessen als eigentliche Triebkraft die Delokalisierung von Elektronen der M-C-Bindung über die gesamte Alkyleinheit fungiert. Im Falle der frühen Übergangsmetalle konnte zudem gezeigt werden, daß dort lokale Ladungskonzentrationen am Zentralmetall eine Schlüsselfunktion einnehmen und diese durch die geeignete Wahl von Liganden manipuliert werden können. So-called agostic interactions between (transition) metal centers and C-H groups of appended ligands are ubiquitous in organometal chemistry and have central relevance to important processes like C-H activation and Ziegler-Natta catalysis. To explore the true nature of this phenomenon experimental and theoretical electron densities of agostic alkyl complexes of lithium and early transition metals were determined and analyzed topologically, using the "Atoms in Molecules" method of Bader. The studies revealed that the observed geometrical distortions in these compounds primarily arise from delocalization of the M-C bonding electrons over the entire alkyl fragment, with direct M...H-C interactions playing only a minor role in stabilizing the structure. In addition, ligand-induced local charge concentrations on transition metal centers were shown to be crucial in the development of agostic interactions.

Published
2004

35. Nature of the Bonding in Metal-Silane σ-Complexes

Author

McGrady, G. Sean, primary, Sirsch, Peter, additional, Chatterton, Nicholas P., additional, Ostermann, Andreas, additional, Gatti, Carlo, additional, Altmannshofer, Sandra, additional, Herz, Verena, additional, Eickerling, Georg, additional, and Scherer, Wolfgang, additional

Published
2009
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38. Cationic rare-earth metal SALEN complexes

Author

Liu, Qiancai, primary, Meermann, Christian, additional, Görlitzer, Hans W., additional, Runte, Oliver, additional, Herdtweck, Eberhardt, additional, Sirsch, Peter, additional, Törnroos, Karl W., additional, and Anwander, Reiner, additional

Published
2008
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50. Vibrational properties and matrix photochemistry of trimethyldioxorhenium(vii), (CH3)3ReO2Electronic supplementary information (ESI) available: further details concerning the vibrational calculations and cartesion coordinates of the optimised geometries. See http://www.rsc.org/suppdata/dt/b2/b204238j/

Author

Downs, Anthony J., primary, Dierker, Gereon, additional, Green, Jennifer C., additional, Greene, Tim M., additional, Sean McGrady, G., additional, Morris, Leigh J., additional, Scherer, Wolfgang, additional, and Sirsch, Peter, additional

Published
2002
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