New dinuclear ruthenium complexes: Structure and oxidative catalysis

Abstract

The synthesis of new dinuclear complexes of the general formula {[Ru II(trpy)]2(μ-pdz-dc)(μ-(L)}+ [pdz-dc is the pyridazine-3,6-dicarboxylate dianion; trpy is 2,2′:6′,2″- terpyridine; L = Cl (1+) or OH (2+)] is described. These complexes are characterized by the usual analytical and spectroscopic techniques and by X-ray diffraction analysis. Their redox properties are characterized by means of cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Complex 2+ is used as the starting material to prepare the corresponding Ru-aqua complex {[RuII(trpy)(H2O)] 2(μ-pdz-dc)}2+ (32+), whose electrochemistry is also investigated by means of CV and DPV. Complex 32+ is able to catalytically and electrocatalytically oxidize water to dioxygen with moderate efficiencies. In sharp contrast, 32+ is a superb catalyst for the epoxidation of alkenes. For the particular case of cis-β-methylstyrene, the catalyst is capable of carrying out 1320 turnovers with a turnover frequency of 11.0 cycles min-1, generating cis-β-methylstyrene oxide stereospecifically. © 2013 American Chemical Society.