Hydrosilane Synthesis by Catalytic Hydrogenolysis of Chlorosilanes and Silyl Triflates

Abstract

Hydrogenolysis of the chlorosilanes and silyl triflates (triflate = trifluoromethanesulfonate, OTf^-) Me_{3- n}SiX_{1+ n} (X = Cl, OTf; n = 0, 1) to hydrosilanes at mild conditions (4 bar of H₂, room temperature) is reported using low loadings (1 mol %) of the bifunctional catalyst [Ru(H)₂CO( HPNP ^iPr)] ( HPNP ^iPr = HN(CH₂CH₂P( iPr)₂)₂). Endergonic chlorosilane hydrogenolysis can be driven by chloride removal, e.g., with NaBAr^F₄ [BAr^F₄^- = B(C₆H₃-3,5-(CF₃)₂)₄^-]. Alternatively, conversion to silyl triflates enables facile hydrogenolysis with NEt₃ as the base, giving Me₃SiH, Me₂SiH₂, and Me₂SiHOTf, respectively, in high yields. An outer-sphere mechanism for silyl triflate hydrogenolysis is supported by density functional theory computations. These protocols provide key steps for synthesis of the valuable hydrochlorosilane Me₂SiClH, which can also be directly obtained in yields of over 50% by hydrogenolysis of chlorosilane/silyl triflate mixtures.