ne. In contrast, zirconocene–alkyne complexes, such as those of 1-(trimethylsilyl)prop-1-yne and diphenylacetylene, gave 1-zirconacyclohept-2-en-5-yne in good yields. Consideration of structural parameters suggests that both a seven-membered cyclic alkyne and a five-membered structure contribute to generation of this complex. Coupling of benzyne and [3]cumulenes on a metal was also found to afford