New rutheniurn(II or III) complexes with general formula [Ru(O-N)(bpy)(2)](n+) (O-N = unsymmetrical bidentate phenolate ligand; bpy = 2,2'-bipyridine) were synthesized, and their crystal structures and electrochemical properties were characterized. Ru-II complexes with, 2-(2-imidazolinyl)phenolate (Himn(-)) or 2-(1,4,5,6-tetrahydropyrimidin-2-yl)phenolate (Hthp(-)) could be deprotonated by addition of excess KO'Bu, although the deprotonated species were easily reprotonated by. exposure to air. Unlike these Run complexes, their Ru-III analogs showed interesting ligand oxidation reactions upon addition of bases. With Ru-III (Himn)(bpy)(2)](2+), two electron oxidation of Himn(-) and reduction of the Rum center resulted in conversion of the 2-irnidazolinyl group, to a 2-imidazolyl group. On the other hand, the corresponding Hthp- complex exhibited four electron oxidation of the ligand to form 2-(2-pyrirnidyl)phenolate (pym-). These aromatization reactions of imidazolinyl and 1,4,5,6-tetrahydropyrimidyl groups were also achieved by the electrochemically generated Rum complexes.'