Photochemical oxidation of [Ir((C³,N′-Hbpy)(bpy)₂)]³⁺ by redox quenching

Aqueous solutions containing [Ir((C³,N′-Hbpy)(bpy)₂)]³⁺ were studied at room temperature by steady and pulsed laser techniques in the presence of electron acceptors. The acceptors used were S₂O₈^2- ions, methylviologen (as nitrate), [Co(NH₃)₅F]²⁺, and Fe³⁺ (as perchlorate). The first three produce [Ir((C³,N′-Hbpy)(bpy)₂)]⁴⁺ while the last produces a complex. The quenching and product decay rate constants, as well as the observed spectra, are reported. The [Ir((C³,N′-Hbpy)(bpy)₂)]⁴⁺ complex, reported here for the first time, is capable of oxidizing Cl^- to Cl^2-. In the absence of additives other than [Co(NH₃)₅F]²⁺ it is stable at pH <1.5 for at least 2 h. The site of oxidation, whether it is the Ir metal or a ligand, is not known.