Elucidation of dioxygen activation mechanism by heme is a pivotal issue in biological and material chemistry. Thus, we synthesized functional heme model complexes to gain insights into the molecular mechanism. Previously, we reported that the reaction of FeIITMPIm with potassium superoxide yielded a novel seven-coordinate (7c) high-spin side-on peroxy complex. The new peroxy species was able to be converted to a six-coordinate (6c) low-spin end-on hydroperoxy complex upon protonation, whereas the original 6c side-on peroxy complex was not. In addition, we have recently studied the one-electron reduction process of the ferric-superoxy species applying cryoradiolytic reduction in conjunction with EPR and rR spectroscopy. The present study emphasizes a crucial role of the axial ligand and a mediator of proton transfer at the distal site of heme in the efficient dioxygen activation.

Spectroscopic insights into the molecular mechanism of dioxygen activation by functional heme models

243rd National Meeting (2012)

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