Biomimetic Studies of Oxidation Reactions by Metalloporphyrins through Ligand Effect and Kinetic Studies of Photo-Generated Porphyrin-Iron(Iv)- Oxocompound II Models

High-valent iron(IV)-oxo porphyrins are the central oxidizing species in hemecontaining enzymes and synthetic oxidation catalysts. Many transition metal complexes have been extensively studied as models of the ubiquitous cytochrome P450 enzymes to probe the sophisticated oxygen atom transfer (OAT) mechanism as well as to invent enzyme-like oxidation catalysts. In this work, two metalloporphyrin complexes have been successfully synthesized, and spectroscopically characterized. A new photochemical entry to porphyrin-iron(IV)-oxo derivatives, commonly referred to as compound II models, was also investigated in two porphyrin ligands that differ in electronic and steric environments. As determined by their distinct UV-vis spectra and kinetic behaviors, iron(IV)-oxo porphyrins [FeIV(Por)O] were successfully produced by visible light irradiation of highly photo-liable porphyrin-iron(III) bromates. The iron(IV)-oxo porphyrins investigated in this study include 5,10,15,20- tetra(pentafluorophenyl)porphyrin-iron(IV)-oxo (4a), and 5,10,15,20-tetra(2,6- difluorophenyl)porphyrin-iron(IV)-oxo (4b)