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.