Neutral Penta- and Hexacoordinate N-Heterocyclic Carbene Complexes Derived from SiX4 (X = F, Br)

Reactions of silicon halides with N-heterocyclic carbene produce neutral penta- of hexacoordinate complexes IPr center dot SiF4 (1), IPr center dot SiF4 center dot IPr (2), and IPr center dot SiBr4 (3) (IPr = :C[N(2,6-iPr(2)-C6H3)-CH](2)). Molecular structures of 1-3 were determined by X-ray diffraction studies and exhibit interesting structural features.