Photoassisted Generation of a Dinuclear Iron(III) Peroxo Species and Oxygen‐Atom Transfer

Abstract

Nature has developed a large variety of metalloenzymes capable of catalyzing selective oxidation reactions through the reductive activation of dioxygen at mono-or dinuclear iron active sites. [1][2][3][4] Among these metalloenzymes, cytochromes P 450 (cytP 450 ), with a mononuclear iron active site, are the most widely known and studied, whereas soluble methane monooxygenase (MMO), which contains a dinuclear iron center, is under intensive investigation.[5] Both systems oxidize a variety of organic substrates by the use of dioxygen and electrons provided by NAD(P)H to give the desired products and water. Much progress has been made in understanding the structure/function relationship of these metalloenzymes on the basis of synthetic systems, [6][7][8] and key intermediates, such as high-valent iron-oxo [9,10] and ironperoxo species [5] have been identified and characterized. However, in most of these synthetic models, the high-valent iron-oxo or iron-peroxo species were generated by the addition of chemical oxidants, such as PhIO, H 2 O 2 , or O 2 , in the presence of electron and proton donors. Gray and coworkers were the first to photogenerate different intermediates of cytP 450 through a photosensitizer-cytP 450 assembly in the presence or the absence of electron scavengers.

The Reactivity of FeII and CoII Disulfide Compounds with Dihydrogen Peroxide

“…UV/Vis spectroscopy showed the reaction to be complete within several minutes, and analysis of a reaction carried out at –78 °C showed that a sulfinato‐iron(III) compound is formed as the first intermediate. Unfortunately, a potential µ‐peroxido‐diiron(III) intermediate such as reported in another study was not observed in our reactions …”

Thermal and photoinduced electron-transfer catalysis of high-valent metal-oxo porphyrins in oxidation of substrates

“…Reductive activation of O 2 in a nonenzymatic system was reported for a diiron(III) complex and a ruthenium(II)-polypyridine-type complex, which acts as a photosensitizer, and triethylamine (TEA), which functions as a sacrificial electron donor [26]. Exposure of the photogenerated diiron(II) complex to O 2 leads to the formation of the diiron(III)-peroxo intermediate responsible for oxygen-atom transfer to triphenylphosphine to produce triphenylphosphine oxide.…”

Photooxidation of triarylphosphines under aerobic conditions in the presence of a gold(iii) complex on cellulose extracted from Carthamus tinctorius immobilized on nanofibrous phosphosilicate

“…Given the importance of this issue, many methods have been extended in these topics. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Despite their signicant results, phosphine oxidation reactions have some problems. A catalytic or stoichiometric amount of additives must be added to initiate or catalyze this reaction.…”

“…Thus, more efficient reactions that can be performed under ambient conditions are in urgent need considering the increasing environmental concerns. Photooxidation [23][24][25][26][27][28][29] provides an efficient way to realize this reaction, which normally uses oxygen as the oxidant. [25][26][27] Gold catalysis has quickly become a hot topic in Chemistry in the past decade.…”