Abstract
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 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 NaBArF4 [BArF4- = 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.
Highlights
Organohydrosilanes are important reagents for olefin hydrosilylation[1] and other applications such as C-H bond silylation,[2] desulfurization of fuels,[3] or dehydrogenative oligo/polysilane formation.[4] (Organo)hydrochlorosilane building blocks SiHxClyRz enable the orthogonal synthesis of branched polysiloxanes and self-healing silicones by sequential polycondensation and cross-linking via hydrosilylation as used e.g. for the fabrication of release coatings, moldings and adhesives.[5]Scheme 1
These protocols provide key steps for the synthesis of the valuable hydrochlorosilane Me2SiClH, which can be directly obtained in yields over 50% by hydrogenolysis of chlorosilane/silyl triflate mixtures
A stoichiometric control experiment confirmed that the trans-dihydride complex [Ru(H)2(CO)(HPNPiPr)] (1) readily reacts with Me3SiCl to the corresponding hydrosilane in almost quantitative spectroscopic yield (Scheme 2)
Summary
Organohydrosilanes are important reagents for olefin hydrosilylation[1] and other applications such as C-H bond silylation,[2] desulfurization of fuels,[3] or dehydrogenative oligo/polysilane formation.[4] (Organo)hydrochlorosilane building blocks SiHxClyRz enable the orthogonal synthesis of branched polysiloxanes and self-healing silicones by sequential polycondensation and cross-linking via hydrosilylation as used e.g. for the fabrication of release coatings, moldings and adhesives.[5]Scheme 1. Conversion to silyl triflates enables facile hydrogenolysis with NEt3 as base, giving Me3SiH, Me2SiH2 and Me2SiHOTf, respectively, in high yields. These protocols provide key steps for the synthesis of the valuable hydrochlorosilane Me2SiClH, which can be directly obtained in yields over 50% by hydrogenolysis of chlorosilane/silyl triflate mixtures.
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