Symmetry states of metalloporphyrin pi-cation radicals, models for peroxidase compound I

Oxoferryl porphyrin pi -cation radical active sites of compound I intermedi ates which, are found in enzymes such as peroxidases and catalases have bee n extensively modeled by oxidized synthetic metalloporphyrins. The electron ic symmetry states of these compounds were initially assigned on the basis of electronic absorption data. in recent years new experimental and theoret ical results have become available which have led to a re-evaluation and mo dification of the original assignments. A historical perspective of these d evelopments is provided in the context of recent NMR, resonance Raman, and other spectroscopic data and theoretical calculations for the synthetic mod els and enzymatic systems. Copyright (C) 2001 John Wiley & Sons, Ltd.