Functional Models for Non-heme Mononuclear Iron Oxygenases

Non-heme mononuclear iron oxygenases catalyze a large number of oxidation reactions in biological systems. The reactions are often proposed to proceed via the intermediacy of high valent Fe(IV) oxo (ferryl) or, Fe(V) oxo (perferryl) intermediates. Therefore, in order to mimic the high valent Fe(IV) oxo chemistry as well as the catalytic processes exhibited by those enzymes, new functional model complexes have been prepared and their reactivities have been studied both experimentally and theoretically. In order to prepare high valent Fe(IV) oxo complexes, two new pentadenate nitrogen donor-based ligands have been synthesized and their Fe(II) complexes have been synthesized and characterized. The Fe(II) complexes have been converted into the corresponding Fe(IV) oxo complexes using suitable oxidant. The Fe(IV) oxo complexes have been characterized by several spectroscopic techniques and their reactivities in C-H activation and the O-atom transfer reaction have been investigated. Theoretical studies have been carried out to investigate the H-atom transfer reaction. The Fe(II) complexes have also been employed in alkane oxidation catalysis using hydrogen peroxide and peracids. To make functional models for Rieske oxygenases, three tetradentate nitrogen-donor based ligands have been prepared. The corresponding Fe(II) complexes have been prepared and characterized. The C-H hydroxylation and C=C oxidation reactions have been studied using these complexes as catalyst and hydrogen peroxide as oxidant. Isotope labeling studies and computational studies have been performed to investigate the reaction mechanisms. A Fe(II) complex of a tetradentate chiral nitrogen-donor based ligand has also been prepared to investigate the asymmetric epoxidation of olefins, using hydrogen peroxide as oxidant