Reactions of Si2Br6 with N-Heterocyclic Carbenes

Article abstract of DOI:10.1002/zaac.201800163

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.