An NHC-Coordinated Silicon/Sulfur Analogue of an Acyl Carbene

Despite great advances in the chemistry of low-valent silicon species, a silicon/sulfur analogue of an acyl carbene, namely a silathioacyl silylene, has remained elusive. Herein, we report that the reaction of dialkyldisilyne 1 with cyclic thiourea 2a affords 3, an N-heterocyclic carbene (NHC) complex of a silathioacyl silylene. The solid-state structure of 3 reveals a three-membered ring with a markedly elongated Si─S bond and an Si-Si single bond, consistent with hitherto unknown intramolecular coordination of the silanethione sulfur to the silylene center, while computational studies indicate negligible disilathiirene character. Compound 3 exhibits silylene-like reactivity toward xylyl isocyanide to give an NHC complex of an imino-substituted silanethione.