Primary photophysical and photochemical processes upon UV excitation of PtBr6 2– and PtCl6 2– complexes in water and methanol

Abstract

Primary photophysical and photochemical processes were studied for PtIVBr62– and PtIVCl62– complexes in water and methanol by ultrafast kinetic spectroscopy upon excitation in the band region of charge transfer from the ligand-centered group π-orbitals to the eg*-orbital of PtIV complex anion (LMCT bands). The data obtained earlier upon excitation in the region of d—d bands were compared. Irrespective of the excitation wavelength, the photochemical properties of complexes are caused by the reactions of intermediates proceeding in the picosecond time range. These intermediates were identified as PtIVBr5– upon photolysis of PtIVBr62– and, presumably, the Adamson radical pair [PtIIICl52–(C4v)...Cl•] upon photolysis of PtIVCl62–. The difference in the exciting light wavelengths has an impact only on the first step of these processes, i.e., transition from the Franck—Condon excited state to intermediates.