Preparation and Characterization of Osmium-Stannyl Polyhydrides: d4-d2 Oxidative Addition of Neutral Molecules in a Late Transition Metal

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• 作者：Miguel A. Esteruelas ; Agustí ; Lledó ; s ; Feliu Maseras ; Montserrat Olivá ; n ; Enrique Oñ ; ate ; Marí ; a A. Tajada ; and Jaume Tomà ; s
• 刊名：Organometallics
• 出版年：2003
• 出版时间：May 12, 2003
• 年：2003
• 卷：22
• 期：10
• 页码：2087 - 2096
• 全文大小：211K
• 年卷期：v.22,no.10(May 12, 2003)
• ISSN：1520-6041

文摘

Complex OsH₂Cl₂(PⁱPr₃)₂ (1) reacts with 2.0 equiv of HSnPh₃ to give the tetrahydride-stannyl derivative OsH₄Cl(SnPh₃)(PⁱPr₃)₂ (2) and ClSnPh₃. The structure of 2 has beendetermined by X-ray diffraction analysis. In the solid state and in solution at temperatureslower than 298 K, the coordination geometry around the osmium atom can be rationalizedas derived from a distorted dodecahedron. In the presence of diphenylacetylene, complex 2gives OsH₃(SnClPh₂){²-CH₂=C(CH₃)PⁱPr₂}(PⁱPr₃) (3), cis-stilbene, and benzene. In the solidstate, the structure of 3 determined by X-ray diffraction analysis can be described as a verydistorted pentagonal bipyramid, with the phosphorus atom of the triisopropylphosphineligand and the midpoint of the olefinic bond of the isopropenyl group of the dehydrogenatedphosphine occupying axial positions. In solution, at temperatures higher than 233 K, thecoordinated olefin is released. Complex 3 reacts with molecular hydrogen to afford thepentahydride OsH₅(SnClPh₂)(PⁱPr₃)₂ (4), as a result of the hydrogenation of the coordinatedolefinic bond and the d⁴-d² oxidative addition of hydrogen. The structure of 4 in the solidstate also has been determined by X-ray diffraction. The coordination geometry around theosmium atom can be rationalized as a distorted dodecahedron. In solution, complex 4 doesnot have a rigid structure even at 193 K. DFT calculations in model systems of 2, 3, and 4,in which the bulky ligands have been replaced by small models, followed by QM/MMoptimizations with the real ligands have allowed the complete determination of the hydridepositions and of the role played by steric effects in the experimental structures.