Alkyne and carbonyl coupling reactions in dimanganese carbonyl complexes. The reactions of Mn2(CO)9(NCMe) with HC.tplbond.CCO2Me

Abstract

Four compounds Mn[sub 2](CO)[sub 8][[mu]-O=C[C(H)=C(CO[sub 2]Me)][sub 2]], 2, 35%, (OC)[sub 4]Mn[trans-[mu]-HC=C(CO[sub 2]Me)]Mn(CO)[sub 5], 3, 3%, (OC)[sub 4]Mn[C(CO[sub 2]Me)=C(H)C(=O)C(H)=C(CO[sub 2] Me)C(H)=C(CO[sub 2]Me)]Mn(CO)[sub 4], 4, 20%, and (OC)[sub 4]Mn[C(CO[sub 2]Me)-C(H)C(=O)C(H)=C(CO[sub 2]Me) C(H) =CH(CO[sub 2]Me)], 5, 5% yield, were obtained from the reaction of Mn[sub 2](CO)[sub 9](MeCN), 1, with HC[triple bond]CCO[sub 2]Me in hexane solvent at 25[degrees]C. Compounds 3-5 are new. Compound 3 is a dimetalated olefin complex formed by the insertion of the alkyne into the metal-metal bond of 1. Compounds 4 and 5 were characterized by a single-crystal X-ray diffraction analysis. Compound 4 contains two metallacyclic rings (one five membered and one six membered) formed by the coupling of three alkynes to one CO ligand. In the five membered ring the oxygen atom of the CO-derived carbonyl group is coordinated to one of the metal atoms. The six membered ring was formed by one of the alkynes and a coordinated carboxylate group from one of the alkynes coupled to it. 9 refs., 2 figs., 7 tabs.