The photooxidation of tetrachloroplatinate(II) in chloroform
[PtCl6]2− is known to be photoreduced by UV light to [PtCl4]2− in chloroform, but at irradiation wavelengths of 254 nm or lower the reverse reaction, photooxidation of [PtCl4]2− to [PtCl6]2−, occurs. This is a solvent-initiated process, proceeding through absorption of light by CHCl3 and subsequent bond homolysis. The quantum yield, based on the light absorbed by CHCl3, is 0.20. Tetrachloroplatinate(II) and hexachloroplatinate(IV) may be cycled back and forth several times by changing the irradiation wavelength.
Patrick E. Hoggard and Arnd Vogler, "The photooxidation of tetrachloroplatinate(II) in chloroform", Inorg. Chim. Acta 348, 229-232 (2003).