Notes. Ligand additivity in the oxidation potentials of bidentate mixed-ligand ruthenium( II ) complexes

Reversible oxidation half-wave potentials E½r have been found to be additive according to the number of ligands x by analysing the potential map of [Ru(bipy)3–xLx]n+ complexes (bipy = 2,2′-bipyridine; L = polypyridine or β-diketone). The slope of plots of E½rvs. x depends on the kind of ligand L and affords a measure of the π-donor/π-acceptor ability of the bidentate ligands. Ligand parameters, PL, for various bidentate ligands, are proposed.