C−C Coupling of a Permetalated Ethene, (μ<sub>4</sub>-CC)Ru<sub>2</sub>(FeCp*)<sub>2</sub>(CO)<sub>10</sub>, with Alkynes, and Isolation of a Labile MeCN Adduct, (μ<sub>4</sub>-CC)Ru<sub>2</sub>(FeCp*)<sub>2</sub>(CO)<sub>8</sub>(NCMe)<sub>2</sub>

A tetranuclear C<sub>2</sub> (dicarbide) cluster complex with a permetallated ethene structure, (μ<sub>4</sub>-CC)Ru<sub>2</sub>(FeCp*)<sub>2</sub>(CO)<sub>10</sub> (<b>2</b>), reacts with alkynes in refluxing THF to give a variety of adducts resulting from C−C coupling and oxidative metallacyclization with the C<sub>2</sub> ligand in addition to a unique μ<sub>4</sub>-dicarbyne complex with a dimetallacyclobutatriene core, (μ<sub>4</sub>-C−C)Ru<sub>2</sub>(FeCp*)<sub>2</sub>(CO)<sub>6</sub>(μ-η<sup>2</sup>:η<sup>2</sup>-PhC⋮CPh). The reactions are initiated by decarbonylation, as confirmed by the reactions of an isolated, labile species lightly stabilized by MeCN, (μ<sub>4</sub>-CC)Ru<sub>2</sub>(FeCp*)<sub>2</sub>(CO)<sub>8</sub>(NCMe)<sub>2</sub>, which undergoes the reactions at room temperature and provides the same types of products as those obtained from <b>2</b>.