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

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.

六(三甲基膦)合钼[Mo(PMe₃)₆]可断裂硅烷（SiH₄）、苯基硅烷（PhSiH₃）与二苯基硅烷（Ph₂SiH₂）的Si-H键，生成一系列新型甲硅烷基、高价甲硅烷基、硅烷及二硅烷配合物，对应实例分别为四(三甲基膦)二(甲硅烷基)二氢合钼[Mo(PMe₃)₄(SiH₃)₂H₂]、四(三甲基膦)(κ²-H₂-二氢二苯基硅基)氢合钼[Mo(PMe₃)₄(κ²-H₂-H₂SiPh₂H)H]、三(三甲基膦)(σ-苯基硅基)四氢合钼[Mo(PMe₃)₃(σ-HSiHPh₂)H₄]以及三(三甲基膦)(κ²-H₂-四苯基二硅烷合)二氢合钼[Mo(PMe₃)₃(κ²-H₂-H₂Si₂Ph₄)H₂]。其中，四(三甲基膦)(κ²-H₂-二氢二苯基硅基)氢合钼与三(三甲基膦)(κ²-H₂-四苯基二硅烷合)二氢合钼分别是首例包含双齿配位高价κ²-H₂-二氢二苯基硅基配体的配合物，以及首例带有螯合二硅烷配体的配合物；二者在氢气氛围下均可转化为二苯基硅烷加合物——三(三甲基膦)(σ-苯基硅基)四氢合钼。四(三甲基膦)二(甲硅烷基)二氢合钼可与四氘代硅烷（SiD₄）发生同位素交换反应；对释放出的SiHₓD₄₋ₓ同位素异构体进行核磁共振（NMR）波谱分析后表明，该反应并非通过初始还原消除硅烷的路径进行，而是经由复分解路径完成。