Electron Transfer Mechanism in the Oxidation of Aryl 1-Methyl-1- phenylethyl Sulfides Promoted by Nonheme Iron(IV)-Oxo Complexes: The Rate of the Oxygen Rebound Process

The oxidation of aryl 1-methyl-1-phenylethyl sulfides promoted by the nonheme iron(IV)-oxo complexes [(N4Py)FeIV?O]2+ and [(Bn-TPEN)FeIV?O]2+ occurs by an electron transfer-oxygen rebound (ET-OT) mechanism leading to aryl 1-methyl-1-phenylethyl sulfoxides accompanied by products derived from C?-S fragmentation of sulfide radical cations (2-phenyl-2-propanol and diaryl disulfides). For the first time, the rate constants for the oxygen rebound process (kOT), which are in the range of <0.8 × 104 to 3.5 × 104 s-1, were determined from the fragmentation rate constants of the radical cations (kf) and the S oxidation/ fragmentation product ratios.