Iron-oxygen intermediates and their applications in biomimetic studies (Chapter 22)

Abstract

Dioxygen molecule (O sub(2)) is an important entity for heme and nonheme iron enzymes as the activation and binding of this molecule to iron triggers catalysis of several metabolic reactions in living nature. The iron-oxygen intermediates are highly reactive species that have been well characterized and exploited in various organic oxidative transformations. A decade and half back, the chemistry of biological iron-oxygen intermediates was just a new area but the momentum of isolation and characterization increased in very recent years. Wonwoo Nam and Larry Que, Jr. have reported several of iron-oxygen intermediates stabilized by nonheme ligands. In high-valent iron-oxygen chemistry, the species Fe sup(II)(O sub(2))-, Fe sup(III)(O sub(2)) sup(2)-, Fe sup(III)(OOH), Fe sup(IV)(O), and Fe sup(V)(O) have been characterized and used in various transformations. The Fe(IV) (O)(iron-oxo) species can oxidize alkanes to alcohols via H-atom abstraction (C-H activation). The oxygen transfer from iron(IV)-oxo to the substrates (S and P-oxidation, epoxidation) have been studied extensively. There is wide scope in investigating Fe(II)-O sub(2) (iron-superoxo) species due to its limited studies. The spectroscopic characterization of Fe(III)-OOH (iron-hydroperoxo) has been reported but structurally it is yet unknown. The chemistry of Fe(III)-O sub(2) (iron-peroxo) species has been well reported in nucleophilic deformylation of aldehydes. A lot of work on the characterization and reactivity of iron(V)-oxo species has only recently been done. These intermediates find various applications in biomimetic chemistry, thus making them versatile reagents for biology.