Cleavage of Unactivated Si−C(sp3) Bonds with Reed's Carborane Acids: Formation of Known and Unknown Silylium Ions

An efficient method for the benzenium‐ion‐mediated cleavage of inert Si−C(sp³) bonds is reported. Various tetraalkylsilanes can thus be converted into the corresponding counteranion‐stabilized silylium ions. The reaction is chemoselective in the case of hexamethyldisilane. Computations reveal a mechanism with backside attack of the proton at one of the alkyl groups. Several activated Si−C(spⁿ) bonds (n=3–1) react equally well, and the procedure can be extended to the generation of stannylium ions.