CYCLOHEXA-1,4-DIENE IN A BRIDGING COORDINATION MODE - SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF RU(5)C(CO)(1)3(MU(2)-ETA(2)ETA(2)-C6H8-1,4) AND RU5C(CO)11(MU(2)-ETA(2)ETA(2)-C6H8-1,4)(2)

Reaction of the square-pyramidal cluster [Ru5C(CO)(15)] with cyclohexa-1,4-diene and Me(3)NO in CH2Cl2 affords the organometallic cluster [Ru5C(CO)(13)(mu(2)-eta(2).eta(2)-C6H8-1,4)] (1). Further reaction of 1 with cyclohexa-1,4-diene and Me(3)NO in CH2Cl2 yields [Ru5C(CO)(11)(mu(2)-eta(2).eta(2)-C6H8-1,4)(2)] (2). The molecular structures of both 1 and 2 have been established by single crystal X-ray analysis. In 1 the diene ligand occupies a radial position bridging two metal atoms on the square base of the cluster, while in 2 the second diene substitutes two axial carbonyl groups on consecutive basal ruthenium atoms. In both clusters, the I,lt-topology of the diene ligand is maintained. Studies of the variation in the H-1 NMR spectrum of 2 with temperature have revealed that as the temperature is raised the two different C6H8 ligands equilibrate.