Reaction of ruthenium and iron alkynyl complexes with [Mo2(CO)4(η-C5H5)2]‡

Abstract

The reaction of the molybdenum dimer [Mo₂(CO)₄(η-C₅H₅)₂] with [M(CCR)(CO)₂(η-C₅H₅)] (M = Ru or Fe, R = Me or Ph) has given different products dependent on the alkynylmetal. The ruthenium-containing starting materials gave the expected dimolybdenum alkynyl adducts as the only isolable materials in moderate yield. In contrast the iron alkynyls underwent Fe–C bond cleavage to give the simple known alkyne adducts [Mo₂(µ-η²-HC₂R)(CO)₄(η-C₅H₅)₂] by a yet to be determined mechanism. The fluxional nature of the complex [Mo₂{Ru(µ-CCMe)(CO)₂(η-C₅H₅)}(CO)₄(η-C₅H₅)₂] was observed by solution NMR studies; the mechanism for equilibration of the molybdenum carbonyl groups at room temperature must involve disruption of the central Mo₂C₂ core.