Hydrosilane Synthesis by Catalytic Hydrogenolysis of Chlorosilanes and Silyl Triflates

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 H 2, room temperature) is reported using low loadings (1 mol %) of the bifunctional catalyst [Ru(H) 2 CO( H PNP i Pr )] ( H PNP i Pr = H N(CH 2 CH 2 P( i Pr) 2 ) 2 ). Endergonic chlorosilane hydrogenolysis can be driven by chloride removal, e.g., with NaBAr F 4 [BAr F 4 – = B(C 6 H 3 -3,5-(CF 3 ) 2 ) 4 – ]. Alternatively, conversion to silyl triflates enables facile hydrogenolysis with NEt 3 as the base, giving Me 3 SiH, Me 2 SiH 2, and Me 2 SiHOTf, 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 Me 2 SiClH, which can also be directly obtained in yields of over 50% by hydrogenolysis of chlorosilane/silyl triflate mixtures.