The complexes [Ru(tpy)(acac)(Cl)], [Ru(tpy)(acac)(H2O)](PF6) (tpy = 2,2’,2"-terpyridine, acacH = 2,4 pentanedione) [Ru(tpy)(C2O4)(H2O)] (C2O42- = oxalato dianion), [Ru(tpy)(dppene)(Cl)](PF6) (dppene = cis-1,2-bis(diphenylphosphino)ethylene), [Ru(tpy)(dppene)(H2O)](PF6)(2), [Ru(tpy)(C2O4)(py)], [Ru(tpy)(acac)(py)](ClO4), [Ru(tpy)(acac)(NO2)], [Ru(tpy)(acac)(NO)] (PF6)(2), and [Ru(tpy)(PSCS)Cl] (PSCS = 1-pyrrolidinedithiocarbamate anion) have been prepared and characterized by cyclic voltammetry and W-visible and FTIR spectroscopy. [Ru(tpy)(acac)(NO2)](+) is stable with respect to oxidation of coordinated NO2- on the cyclic voltammetric time scale. The nitrosyl [Ru(tpy)(acac)(NO)](2+) falls on an earlier correlation between v(NO) (1914 cm(-1) in KBr) and E(1/2) for the first nitrosyl-based reduction 0.02 V vs SSCE. Oxalate ligand is lost from [Ru-II(tpy)(C2O4)(H2O)] to give [Ru(tpy)(H2O)(3)](2+).