Synthetic routes to ruthenium(II) species containing carboxylate-functionalized 2,2 '-bipyridine ligands

Two methods are reported for the incorporation of carboxylate substituents on polypyridyl ligands coordinated to ruthenium(II) centres. In the first, a precursor complex is synthesized with ethoxycarbonyl groups which are subsequently base-hydrolysed to produce the carboxylate in high yield (-CO₂Et → -CO₂H). In the second method, ruthenyl (Ru^IV=O) species were used to chemically catalyse the electochemical oxidation of methyl substituents on the ligands of a precursor complex to produce the target carboxylate species (-CH₃ → -CO₂H)