NHC-Stabilized Silicon–Carbon Mixed Cumulene

The NHC-stabilized silicon–carbon mixed cumulene (Me₃Si)₂CSi­(IPr)Si­(IPr)C­(SiMe₃)₂ (3, IPr = 1,3-diisopropyl-4,5-dimethyl-imidazol-2-ylidene) has been prepared by reaction of Ar­(SiMe₃)­NK with the NHC-stabilized silene (Me₃Si)₂CSi­(SiMe₃)­Cl­(IPr) (2) in toluene at low temperature via the elimination of trimethylsilyl and chloride groups from 2. X-ray crystal analysis of 3 indicated the formal CSiSiC cumulene skeleton with the short Si–Si double bond distance of 2.1896(10) Å. DFT calculations disclosed its zwitterionic character. Reaction of 3 with diphenylacetylene resulted in the formation of a silatriafulvene with an exocyclic NHC-stabilized silene moiety.