Reactivity of [Ru3(μ-H)(μ-Me2pz)(CO)10] with 2,4-hexadiyne. Characterization of the first tetranuclear ynenyl complex

The tetranuclear ynenyl complex [Ru4(μ-η2-Me2pz)(μ4-η4-MeCHCCCMe)(μ-CO)(CO)10] (Me2pz=3,5-dimethylpyrazolate) has been prepared by reaction of [Ru3(μ-H)(μ-η2-Me2pz)(CO)10] with 2,4-hexadiyne and has been characterized by X-ray diffraction methods. It consists of an unusual broken-wing butterfly (spiked triangle) tetraruthenium framework (64-electron) with all the metal atoms bridged by a hex-2-yn-4-en-4-yl ligand (7-electron donor). This type of coordination is unprecedented for ynenyl ligands.