Lewis Base Catalyzed Selective Chlorination of Monosilanes

A preparatively facile, highly selective synthesis of bifunctional monosilanes R 2 SiHCl, RSiHCl 2 and RSiH 2 Cl is reported. By chlorination of R 2 SiH 2 and RSiH 3 with concentrated HCl/ether solutions, the stepwise introduction of Si−Cl bonds is readily controlled by temperature and reaction time for a broad range of substrates. In a combined experimental and computational study, we establish a new mode of Si−H bond activation assisted by Lewis bases such as ethers, amines, phosphines, and chloride ions. Elucidation of the underlying reaction mechanisms shows that alcohol assistance through hydrogen‐bond networks is equally efficient and selective. Remarkably, formation of alkoxysilanes or siloxanes is not observed under moderate reaction conditions.