A unified survey of Si-H and H-H bond activation catalysed by electron-deficient boranes.

The bond activation chemistry of B(C6F5)3 and related electron-deficient boranes is currently experiencing a renaissance due to the fascinating development of frustrated Lewis pairs (FLPs). B(C6F5)3's ability to catalytically activate Si–H bonds through η1 coordination opened the door to several unique reduction processes. The ground-breaking finding that the same family of fully or partially fluorinated boron Lewis acids allows for the related H–H bond activation, either alone or as a component of an FLP, brought considerable momentum into the area of transition-metal-free hydrogenation and, likewise, hydrosilylation. This review comprehensively summarises synthetic methods involving borane-catalysed Si–H and H–H bond activation. Systems corresponding to an FLP-type situation are not covered. Aside from the broad manifold of CX bond reductions and CX/C–X defunctionalisations, dehydrogenative (oxidative) Si–H couplings are also included.