Pentadiynylidyne and Pentacarbido Complexes.

The reaction of the halocarbyne [W(≡CBr)(CO)2 (Tp*)] (Tp*=hydrotris(3,5-dimethylpyrazol-1-yl)borate) with trimethylsilyl-butadiyne, mediated by [Pd(PPh3 )4 ] and CuI, affords the first pentadiynylidyne complex [W(≡CC≡CC≡CSiMe3 )(CO)2 (Tp*)]. Desilylation provides a general route to heterobimetallic pentacarbido complexes, including [(Tp*)(CO)2 W(μ-C5 )(PPh3 )2 Ru(η-C5 H5 )] and [(Ph3 P)2 (CO)HIr{(μ-C5 )W(CO)2 (Tp*)}2 ].