Reactions of Benzylidene(Pentacarbonyl) Complexes

Benzylidene(pentacarbonyl) complexes of chromium, molybdenum, and tungsten can be prepared from pentacarbonyl[α-alkoxybenzyl] metal-lates by alkoxide abstraction with tetrafluoroboric acid. The extreme electrophilicity of their benzylidene carbon atoms dominates their reactivities. They react readily, even at low temperatures, with a large number of nucleophiles (phosphines, ethers, thioethers, carbon monoxide, alkenes, conjugated diolefines, and alkynes), giving coupling products, both those eliminated from the metal and those still coordinated.