Unprecedented Reactivities of Highly Reactive Manganese(III)-Iodosylarene Porphyrins in Oxidation Reactions

Abstract

We report that Mn(III)-iodosylarene porphyrins, [Mn-III(Porp)((ArIO)-Ar-s)](+), are capable of activating the C-H bonds of hydrocarbons, including unactivated alkanes such as cyclohexane, with unprecedented reactivities, such as a low kinetic isotope effect, a saturation behavior of reaction rates, and no electronic effect of porphyrin ligands on the reactivities of [Mn-III(Porp)((ArIO)-Ar-s)](+). In oxygen atom transfer (OAT) reactions, the sulfoxidation of para-X-substituted thioanisoles by [Mn-III(Porp)((ArIO)-Ar-s)](+) affords a very unusual behavior in the Hammett plot with the saturation behavior of reaction rates and no electronic effect of porphyrin ligands on reactivities. The reactivities and mechanisms of [Mn-III(Porp)((ArIO)-Ar-s)](+) are then compared with those of the corresponding Mn-IV(Porp)(O) complex. The present study reports the first example of highly reactive Mn(III)-iodosylarene porphyrins with unprecedented reactivities in C-H bond activation and OAT reactions.