Syntheses, characterization and redox properties of di- and poly-phosphine linked oligomeric complexes of oxo-centered triruthenium clusters

A series of phosphine-linked oligomers of oxo-centered triruthenium-acetate clusters have been prepared by the reaction of [Ru3O(OAc)6(py)2(CH3OH)](PF6) (1) with di- or poly-phosphine. They have been characterized by elemental analysis, ESI-MS spectrometry, UV–Vis, IR, and 31P NMR spectroscopy, and cyclic and differential pulse voltammetry. The structures of diphosphine-linked dimeric compounds 4 and 7 were determined by X-ray crystallography. As revealed by redox wave splitting, weak to moderate electronic communication is operative between triruthenium clusters across bridging di- or poly-phosphine. With increase of the methylene number in Ph2P(CH2)nPPh2, electronic communication decreases rapidly in diphosphine-linked dimeric complexes [{Ru3O(OAc)6(py)2}2{μ-Ph2P(CH2)nPPh2}]2+ (n = 1–5).