title: Reactions of metalloalkynes. New C2 bonding mode in a trimetallic complex.
abstract: The reaction of the silver complexes [((Ru(CO)2(eta-C5H4R))2(mu-C identical to C))3Ag3][BF4]3 (R = H or Me) with [RuCl(CO)2(eta-C5H4R)] at room temperature gave the new trimetallic complexes [(Ru(CO)2(eta-C5H4R))3(eta 1:eta 2-C identical to C))][BF4] which contain the C2(2-) ligand surrounded by ruthenium atoms; these complexes do not contain metal-metal bonds and were characterised by single crystal X-ray studies; the solid state structure is not retained in solution, where it is found to be fluxional on the NMR timescale and the dynamic process postulated could be described as 'bearing-like'.