The synthesis and characterization of a series of first-row transition metal complexes of 2,2':6',2''-terpyridine 1,1''-dioxide (terpyO(2)) are reported. Four new bis complexes [M(terpyO(2))]X-2 (M = Mn(II), Fe(II), Co(II), and Ni(II); X = ClO4- and BF4-) and one mono complex [Cu(terpyO(2))(H2O)](ClO4)(2) were isolated and characterized, and electrochemical properties were examined. [GRAPHICS]