| Abstract
| - The oxidation of a series of para-substituted phenyl methyl sulfides was carried out with severaloxo(salen)iron (salen = N,N‘-bis(salicylidine)ethylenediaminato) complexes in acetonitrile. Theoxo complex [OFeIV(salen)]•+, generated from an iron(III)−salen complex and iodosylbenzene,effectively oxidizes the organic sulfides to the corresponding sulfoxides. The formation of[OFeIV(salen)]•+ as the active oxidant is supported by resonance Raman studies. The kineticdata indicate that the reaction is first-order in the oxidant and fractional-order with respectto sulfide. The observed saturation kinetics of the reaction and spectral data indicate that thesubstrate binds to the oxidant before the rate-controlling step. The rate constant (k) values for theproduct formation step determined using Michaelis−Menten kinetics correlate well with Hammettσ constants, giving reaction constant (ρ) values in the range of −0.65 to −1.54 for different oxo(salen)iron complexes. The log k values observed in the oxidation of each aryl methyl sulfide bysubstituted oxo(salen)iron complexes also correlate with Hammett σ constants, giving positive ρvalues. The substituent effect, UV−vis absorption, and EPR spectral studies indicate oxygen atomtransfer from the oxidant to the substrate in the rate-determining step.
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