The synthesis of heteronuclear clusters containing cyclopentadienyl- or pentamethylcyclopentadienyliridium and ruthenium or osmium

The reaction of Cp*Ir(CO)2 or CpIr(CO)2 with Ru3(CO)12 under a hydrogen atmosphere afforded the heterometallic clusters Cp*IrRu3(μ-H)2(CO)10 and CpIrRu3(μ-H)2(CO)10, respectively, in moderate yields. In the former reaction, the tetrahydrido cluster Cp*IrRu3(μ-H)4(CO)9 was also formed in trace amounts, although this cluster can be obtained in high yields by the hydrogenation of Cp*IrRu3(μ-H)2(CO)10; the Cp analogue was not obtainable. The reaction of Os3(μ-H)2(CO)10 with Cp*Ir(CO)2 afforded the osmium analogue Cp*IrOs3(μ-H)2(CO)10 in 70% yield, along with a trace amount of the pentanuclear cluster Cp*IrOs4(μ-H)2(CO)13. Hydrogenation of Cp*IrOs3(μ-H)2(CO)10 afforded Cp*IrOs3(μ-H)4(CO)9 in excellent yield. The reaction of Cp*Ir(CO)2 with Os3(CO)10(CH3CN)2 afforded the known trinuclear cluster Cp*IrOs2(CO)9 and the novel cluster Cp*IrOs3(CO)11. Solution-state NMR studies show that the hydrides in the iridium–ruthenium clusters are highly fluxional even at low temperatures while those in the iridium–osmium clusters are less so.