New triosmium-iridium clusters:: Synthesis and molecular structure of [Os3Ir2(Cp*)2(μ-OH)(μ-CO)2(CO)8Cl] (1), [Os3IrCp*(μ-OH)(CO)10Cl] (2), [Os3IrCp*(μ-H)(μ-Cl) (η3,μ3-C5H2N(NH2)Br)(CO)9] (3) and [Os3IrCp*(μ-Cl)2 (η2,μ3-C5H3N(NH)Br)(CO)7] (4)

The trinuclear osmium carbonyl cluster, [Os(3)(CO)(10)(MeCN)(2)], is allowed to react with 1 equiv. of [IrCp*Cl(2)](2) (Cp* = pentamethylcyclopentadiene) in refluxing dichloromethane to give two new osmium-iridium mixed-metal clusters, [Os(3)Ir(2)(Cp*)(2)(mu-OH) (mu-CO)(2)(CO)(8)Cl] (1)and [Os(3)IrCp*(mu-OH)(CO)(10)Cl] (2), in moderate yields. In the presence of a pyridyl ligand, [C(5)H(3)N(NH(2))Br], however, the products isolated are different. Two osmium-iridium clusters with different coordination modes of the pyridyl ligand are afforded, [Os(3)IrCp*(mu-H)(mu-Cl)(eta(3),mu(3)-C(5)H(2)N(NH(2))Br)(CO)(9)] (3)and [Os(3)IrCp*(mu-Cl)(2) (eta(2),mu(3)-C(5)H(3)N(NH)Br)(CO)(7)] (4). All of the new compounds are characterized by conventional spectroscopic methods, and their structures are determined by single-crystal X-ray diffraction analysis. (C) 2007 Elsevier B.V. All rights reserved.