Hydrosilane Synthesis by Catalytic Hydrogenolysis of Chlorosilanes and Silyl Triflates

Hydrogenolysis of the chlorosilanes and silyl triflates (triflate = trifluoromethanesulfonate, OTf-) Me3-nSiX1+n (X = Cl, OTf; n = 0, 1) to hydrosilanes at mild conditions (4 bar of H-2, room temperature) is reported using low loadings (1 mol %) of the bifunctional catalyst [Ru(H)(2)CO(HPNPiPr)] (HPNPiPr = HN-(CH2CH2P(iPr)(2))(2)). Endergonic chlorosilane hydrogenolysis can be driven by chloride removal, e.g., with NaBAr4F [BAr4F- = 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.