C−C Coupling of a Permetalated Ethene, (μ4-CC)Ru2(FeCp*)2(CO)10, with Alkynes, and Isolation of a Labile MeCN Adduct, (μ4-CC)Ru2(FeCp*)2(CO)8(NCMe)2

A tetranuclear C2 (dicarbide) cluster complex with a permetallated ethene structure, (μ4-CC)Ru2(FeCp*)2(CO)10 (2), reacts with alkynes in refluxing THF to give a variety of adducts resulting from C−C coupling and oxidative metallacyclization with the C2 ligand in addition to a unique μ4-dicarbyne complex with a dimetallacyclobutatriene core, (μ4-C−C)Ru2(FeCp*)2(CO)6(μ-η22-PhC⋮CPh). The reactions are initiated by decarbonylation, as confirmed by the reactions of an isolated, labile species lightly stabilized by MeCN, (μ4-CC)Ru2(FeCp*)2(CO)8(NCMe)2, which undergoes the reactions at room temperature and provides the same types of products as those obtained from 2.