C-H and C-C bonds activation by iridium clusters: Synthesis and solid state structure of [Ir-6(CO)(14)(mu(3)-eta(1):eta(2):eta(1)-C7H8)]

The reaction between norbornene (C7H10) and Ir-6(CO)(16) in refluxing toluene yields the substituted cluster [Ir-6(CO)(14)(C7H8)]. In the solid state, the six iridium atoms define an octahedral metal cage, and one face is capped by the C7H8 ligand, coordinated through a 1,2-vinylidene unit. The loss of two hydrogen atoms from the olefin is, presumably, the result of a double oxidative addition of its C-H bonds, followed by elimination of a hydrogen molecule from the cluster. The bonding parameters of the organic fragment, as well as the architecture of the carbonyl ligands, closely match those found in the alkyne-substituted [Ir-6(CO)(14)(PhCCPh)] complex. The cluster [Ir-6(CO)(14)(C7H8)] was characterized through H-1-, C-13- and bidimensional COSY NMR.