Oxidation of Aryl Diphenylmethyl Sulfides promoted by a Nonheme Iron(IV)-Oxo Complex: Evidence for an Electron Transfer-Oxygen transfer mechanism

The oxidation of a series of aryl diphenylmethyl sulfides (4-X-C6H4SCH(C6H5)2 promoted by the nonheme iron(IV)-oxo complex [(N4Py)FeIV=O]2+ occurs by an electron transfer-oxygen transfer (ET-OT) mechanism as supported by the observation of products (diphenylmethanol, benzophenone, and diaryl disulfides) deriving fromα-C−S andα-C−H fragmentation of radical cations, formed besides the S-oxidation products (aryl diphenylmethyl sulfoxides). The fragmentation/S-oxidation product ratios regularly increase through a decrease in the electron-donating power of the aryl substituents, that is, by increasing the fragmentation rate constants of the radical cations as indicated by a laserflash photolysis (LFP) study of the photochemical oxidation of the sulfides carried out in the presence of N-methoxyphenanthridinium hexafluorophosphate.