Synthesis and characterisation of tetraosmium carbonyl clusters bearing an azo type ligand: crystal and molecular structures of [Os 4(μ-H) 4(CO) 11(NC 5H 4NNPh)] and [Os 4(μ-H) 4(CO) 10(MeCN)(NC 5H 4NNPh)

Abstract

Reaction of [Os 4(μ-H) 4(CO) 10(MeCN) 2] with one equivalent of 4-phenylazopyridine (4-PAP) in CH 2Cl 2 at ambient conditions afforded two new tetraosmium clusters [Os 4(μ-H) 4(CO) 11(NC 5H 4NNPh)] ( 1) and [Os 4(μ-H) 4(CO) 10(MeCN)(NC 5H 4NNPh)] ( 2) in moderate yields. Compound 1 exists as a pair of isomers in solution, which differ in the location of the bridging hydride ligands. The molecular structures of clusters 1 and 2 consist of a highly distorted tetrahedral metal skeleton, with the azo ligand terminally bonded to an osmium atom.