The photoreduction of (Bu4N)2[PtCl6] in CHCl3 under 297 nm irradiation to yield [PtCl4]2− follows a rate law proportional to Io1/2f1/2[PtCl6]2−, where f is the fraction of light absorbed by [PtCl6]2−, consistent with a chain mechanism in which the termination step is the dimerization of an intermediate radical, suggested to be CCl3. The same rate law appears to apply in CH3OH.
