Formal SiH4 chemistry using stable and easy-to-handle surrogates

Abstract

Monosilane (SiH₄) is far less well behaved than its carbon analogue methane (CH₄). It is a colourless gas that is industrially relevant as a source of elemental silicon, but its pyrophoric and explosive nature makes its handling and use challenging. Consequently, synthetic applications of SiH₄ in academic laboratories are extremely rare and methodologies based on SiH₄ are underdeveloped. Safe and controlled alternatives to the substituent redistribution approaches of hydrosilanes are desirable and cyclohexa-2,5-dien-1-ylsilanes where the cyclohexa-1,4-diene units serve as placeholders for the hydrogen atoms have been identified as potent surrogates of SiH₄. We disclose here that the commercially available Lewis acid tris(pentafluorophenyl)borane, B(C₆F₅)₃, is able to promote the release of the Si–H bond catalytically while subsequently enabling the hydrosilylation of C–C multiple bonds in the same pot. The net reactions are transition-metal-free transfer hydrosilylations with SiH₄ as a building block for the preparation of various hydrosilanes.