Reactions of Si2Br6 with N‐Heterocyclic Carbenes.

A combined experimental and theoretical study on the reaction of Si2Br6 with N‐heterocyclic carbenes is reported. Employment of an imidazole‐2‐ylidene with methyl groups in C4‐ and C5‐position results in the disproportionation of Si2Br6 into the adducts NHC→SiBr2 and NHC→SiBr4. According to expectation, the hydrogenated derivative 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene forms analogous disproportionation products of Si2Br6 at low temperatures, whereas reaction at higher temperatures furnishes the 4‐SiBr3‐substituted NHC. The underlying formation mechanism explored by means of density functional theory calculations features an abnormal carbene intermediate. [ABSTRACT FROM AUTHOR]