Intermediates formed by laser flash photolysis of [PtCl6]2− in aqueous solutions
Abstract
The stationary photolysis of [PtCl6]2− in aqueous solutions (10−5–10−4 M) at the region of 313 nm leads to its photoaquation with a quantum yield of 0.19. Laser flash photolysis experiments (308 nm) provided evidence of the formation of Pt(III) intermediates, namely [PtCl4(OH)(H2O)]2− and [PtCl4]−, and Cl2˙− radical anions. The Pt(III) complexes formed as a result of an intrasphere electron transfer from Cl− ligands to the excited Pt(IV) ion. However, the main (∼90%) photolysis channel was not accompanied by the transfer of Cl atoms to the solvent bulk. The photoaquation of [PtCl6]2− results from the back electron transfer in the secondary geminate pair, [PtCl5(H2O)]2−–Cl. The relative yield of Pt(III) intermediates, recorded after the completion of all processes in the geminate pair, was less than 10% of the number of disappearing initial [PtCl6]2− complexes.