Dicarbonylcyclopentadienyliridium, (η-C5H5)Ir(CO)2, as a ligand

Abstract

The following complexes, in which CpIr(CO)2 acts as a 2e donor ligand, have been prepared: Cp(OC)2IrW(CO)5 (1), Cp(OC)2IrRu(CO)3(SiCl3)2, Cp(OC)2IrOs(CO)3(GeCl3)(Cl) (2), Cp(OC)2IrOs(CO)3(X)2 (X = Cl, Br (3), I). The characterization of the complexes included the crystal structures of 1, 2, and 3, which reveal that all contain an unbridged metal-metal bond. The carbonyl ligands of 1 in solution undergo exchange on the NMR time scale above -40°C. With the exception of 2, all the complexes dissociate in solution at room temperature, some rapidly so. Only in the case of 3 is an equilibrium with the dissociation products established. The results indicate that CpIr(CO)2 is a weak ligand.Key words: tungsten, osmium, iridium, binuclear.