Synthesis, structure, and reactivities of the Ru–Co heterobimetallic complex. Molecular structures of Cp*Ru(CO) 2(μ 2-CO)Co(CO) 3, Cp*Ru(μ 2-CO) 2(μ 2-dppm)Co(CO) 2, Cp*Ru(CNBu t)(CO)(μ 2-CO)Co(CO) 3, and Cp*(CO)Ru{η 2:η 4–μ 2–C(Tol)CHC(Tol)CH}Co(CO) 2 (Cp*=η 5-C 5Me 5, dppm=Ph 2PCH 2PPh 2, Tol=C 6H 4Me-4)

Abstract

Treatment of Cp*Ru(CO) 2Cl (Cp*=η 5-C 5Me 5) with NaCo(CO) 4 produces the metal–metal bonded heterobimetallic complex Cp*Ru(CO) 2(μ 2-CO)Co(CO) 3 ( 2b). Substitution of the CO ligands by the Ph 2PCH 2PPh 2 (dppm) leads to the isolation of Cp*Ru(μ 2-CO) 2(μ 2-dppm)Co(CO) 2 ( 3) whereas that by Bu t NC gives Cp*Ru(CO)(CNBu t )(μ 2-CO)Co(CO) 3 ( 4). Stoichiometric head-to-tail dimerization of p-tolylacetylene at the bimetallic site of 2b proceeds to form the dinuclear metallacyclopentadiene complex Cp*(CO)Ru{η 2:η 4-μ 2-C(Tol)CHC(Tol)CH}Co(CO) 2 ( 5) in which two alkyne molecules are coupled to form a ruthenacyclopentadiene core which coordinates to the Co(CO) 2 fragment. On the other hand, catalytic head-to-head coupling of methyl propiolate in the presence of 2b yields ( E)-(MeO 2C)CHCH(CCCO 2Me) ( 6). The molecular structures of 2b, 3, 4, and 5 have been determined by X-ray crystallography.