Conversion of an Acetylide−Silylene Complex to an Alkenylcarbyne Complex by Consecutive Ketone Addition and Base-Induced Silanone Elimination

A new acetylide−silylene complex, Cp*(CO)<sub>2</sub>W(SiPh<sub>2</sub>)(CCSiMe<sub>3</sub>) (<b>4</b>), was synthesized by the reaction of Cp*(CO)<sub>2</sub>W(NCMe)Me with Ph<sub>2</sub>HSiCCSiMe<sub>3</sub>. Complex <b>4</b> reacted with acetone to give the six-membered cyclic vinylidene complex Cp*(CO)<sub>2</sub>WCC(SiMe<sub>3</sub>)CMe<sub>2</sub>OSiPh<sub>2</sub> (<b>5</b>) by acetone insertion into the acetylide−silylene framework. Treatment of <b>5</b> with 4-(dimethylamino)pyridine resulted in the formation of the alkenylcarbyne complex Cp*(CO)<sub>2</sub>WCC(CMe<sub>2</sub>)SiMe<sub>3</sub> (<b>8</b>) and cyclic diphenylsiloxanes.