Ru complexes containing pyridine dicarboxylate ligands: electronic effects on their catalytic activity toward wateroxidation

Abstract

Two series of mononuclear ruthenium complexes [Ru(pdc)L3] (H2pdc = 2,6-pyridinedicarboxylic acid; L = 4-methoxypyridine, 1; pyridine, 2; pyrazine, 3) and [Ru(pdc)L2(dmso)] (dmso = dimethyl sulfoxide; L = 4-methoxypyridine, 4; pyridine, 5) were synthesized and spectroscopically characterized. Their catalytic activity toward water oxidation has been examined using Ce(IV) (Ce(NH4)2(NO3)6) as the chemical oxidant under acidic conditions. Complexes 1, 2 and 3 are capable of catalyzing Ce(IV)-driven water oxidation while 4 and 5 are not active. Electronic effects on their catalytic activity were illustrated: electron donating groups increase the catalytic activity.