Irradiation of Rh-2(O2CCH3)(4)(H2O)(2) with visible light in the presence of electron accepters results in the formation of the oxidized complex, Rh-2(O2CCH3)(4)- (H2O)(2)(+). Photogenerated Rh-2(O2CCH3)(4)(H2O)(2)(+) is able to cleave plasmid DNA, whereas the Rh-2(O2CCH3)(4)(L)(2)(+) complexes with nonlabile axial ligands, L, such as py (pyridine) and PPh3 (triphenylphosphine), do not cleave the double helix. Rh-2(O2CCH3)(4)(H2O)(2)(+) [GRAPHICS]