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.