Part I. Coordination Chemistry of High-Valent Osmium Polyanionic Chelating Ligand Complexes with Imine, Imido and Nitrido Ligands. Part II. Asymmetric Hydrogenation Using a Resolved Chiral Scandium Hydride Complex

Citation

Barner, Claudia Jane (1990) Part I. Coordination Chemistry of High-Valent Osmium Polyanionic Chelating Ligand Complexes with Imine, Imido and Nitrido Ligands. Part II. Asymmetric Hydrogenation Using a Resolved Chiral Scandium Hydride Complex. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/tj33-3482. https://resolver.caltech.edu/CaltechETD:etd-06112007-095040

Abstract

Part I: The chemistry of high-valent osmium polyanionic chelating ligand complexes with imine, imido and nitrido ligands is explored. The synthesis and x-ray diffraction study of Os(η⁴-HBA-B)(NC₆H₅NHC₆H₄) is reported. A neutral, octahedral Os(VIII) intermediate complex is postulated. The synthesis and x-ray diffraction study of [OsN(η⁴-HBA-B)]- is reported. The mechanism of formation is discussed. These complexes represent two of the first examples of non-planar amide ligands in transition metal chemistry. The synthesis of a five-coordinate imido complex, Os(N-C₁₀ H₁₆), is reported. The formation of the first osmium-osmium quadruply-bonded complex, [Os(η⁴-HBA-B)]₂, is reported. Reactions with the nitrido complex, [OsN(η⁴-HBA-B)]⁻,and the methylimido complex, OsNMe(η⁴-HBA-B), are also reported.

Part II: The asymmetric hydrogenation of the prochiral substrate, methylene indane, is induced by the resolved chiral scandium complex, Me₂Si(η⁵-C₅Me₄)(η⁵-(C₅H₃(1R,2R,5S)-menthyl)ScH, in substoichiometric quantities. Methylene indane is hydrogenated to produce methylindane with an enantiomeric excess of 34% and a maximum turnover of four.

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