Reactivity of Ru(H)(H2)Cl(PCy3)2 with Propargyl and Vinyl Chlorides: New Methodology To Give Metathesis-Active Ruthenium Carbenes

A procedure for generating the ruthenium hydride complex Ru(H)(H2)Cl(PCy3)2 in 95% yield is presented. Following a novel insertion−elimination pathway, this hydride can react with propargyl or vinyl halides to make metathesis-active vinyl and alkyl carbene species with the general formulas (PCy3)2Cl2RuCH−CHCR2 and (PCy3)2Cl2RuCHR, respectively. Tertiary propargyl chlorides work best, giving Ru−vinyl carbenes in extremely high yield.