Photochemistry of dimeric and trimeric hydroxo-bridged diammine platinum(II) complexes in aqueous solution

The irradiation of aerated aqueous solutions containing cis-Pt(NH3)2(H2O)2+2 with 254-nm light gives rise to the formation of a blue product identified as a mixed valence (Pt(II)/Pt(IV) = 2) hydroxo bridged trinuclear cationic complex [Pt3(NH3)4(OH)6]2+. The photoreactive species have been identified as the dimeric and trimeric hydroxo bridged platinum compounds that are present in solution and have the maximum concentration at pH 6.5. The reaction is initiated in a OH → Pt charge transfer excited state, to give a primary photoreaction intermediate which undergoes thermal air oxidation to give the final blue product. © 1982.