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Si–H and Si–C Bond Cleavage Reactions of Silane and Phenylsilanes with Mo(PMe3)6: Silyl, Hypervalent Silyl, Silane, and Disilane Complexes

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posted on 11.06.2014, 00:00 authored by Ashley A. Zuzek, Gerard Parkin
Mo­(PMe3)6 cleaves the Si–H bonds of SiH4, PhSiH3, and Ph2SiH2 to afford a variety of novel silyl, hyper­valent silyl, silane, and disilane complexes, as respectively illustrated by Mo­(PMe3)4­(SiH3)2H2, Mo­(PMe3)4­(κ2-H2-H2SiPh2H)­H, Mo­(PMe3)3­(σ-HSiHPh2)­H4, and Mo(PMe3)3­(κ2-H2-H2Si2­Ph4)­H2. Mo­(PMe3)4­(κ2-H2-H2SiPh2H)H and Mo­(PMe3)3­(κ2-H2-H2Si2Ph4)­H2 are respectively the first examples of complexes that feature a hypervalent κ2-H2-H2SiPh2H silyl ligand and a chelating disilane ligand, and both compounds convert to the diphenylsilane adduct, Mo­(PMe3)3­(σ-HSiHPh2)­H4, in the presence of H2. Mo­(PMe3)4­(SiH3)2H2 undergoes isotope exchange with SiD4, and NMR spectroscopic analysis of the SiHxD4–x isotopologues released indicates that the reaction does not occur via initial reductive elimination of SiH4, but rather by a metathesis pathway.