The photohydrochlorination of platinum(IV) chloride
When irradiated at 240 nm, PtCl4 in CHCl3 is converted to H2PtCl6. When irradiated at wavelengths longer than 265 nm, PtCl4 is converted to H2PtCl4 and H2PtCl6 in equal amounts. The latter reaction is suggested to proceed by dissociation of chlorine from a ligand to metal charge transfer excited state of Pt(IV) through a Pt(III) intermediate that disproportionates. The 240 nm photoreaction includes a second, solvent-initiated pathway, suggested to involve CCl3 radicals from the photolysis of chloroform, which attack the PtCl4 oligomer to create a Pt(V) intermediate.
Patrick E. Hoggard, Adam J. Bridgeman, Horst Kunkely, and Arnd Vogler, “The photohydrochlorination of platinum(IV) chloride”, Inorg. Chim. Acta 357, 639-643 (2004).