Synthesis of Osmium-Palladium Mixed-Metal Clusters with 2-(diphenylphosphino)pyridine as a Bridging Ligand

Reaction of the pentanuclear cluster [Os5C(CO)14(PPh2Py)] in CH2Cl2with 1.2 equivalents of Pd(MeCN)2Cl2led to the high-yield synthesis of the new osmium-palladium carbonyl cluster [Os5PdC(CO)14(μ-Cl)Cl(μ-PPh2py)] 1. Cluster 1 is thermally unstable and converts slowly in refluxing CHCl3to [{Os4C(CO)10(μ-Cl)(μ-PPh2py)}(μ4-Pd){Os4C(CO)12(μ-Cl)}] 2 and [{Os4(μ5-C)(CO)12(μ-Cl)}2(μ-Pd2Cl2)] 3 in 4% and 67% yield, respectively. Reaction of 1 with iodine gave [Os5PdC(CO)14(μ-Cl)I(μ-PPh2py)] 4 and [{Os4(μ5-C)(CO)12(μ-I)}2(μ-Pd2I2)] 5 in moderate yields. All complexes have been characterized by spectroscopic and single-crystal X-ray diffraction analysis.