Diiron N-bridged species bearing phthalocyanine ligand catalyzes oxidation of methane, propane and benzene under mild conditions

Abstract

Transformation of methane, the most abundant and the least reactive compound of natural gas to valuable products is one of the most difficult chemical problems of great practical importance. In Nature, methane monooxygenase enzymes transform methane to methanol in water under physiological conditions. However, chemical analogs for such a transformation are unknown. Here, we show the mild and efficient aqueous oxidation of methane by hydrogen peroxide, an ecologically and biologically relevant oxidant catalyzed by supported μ-nitrido diiron phthalocyanine dimer, (FePctBu4)2N . This bio-inspired complex containing a stable Fe – N – Fe motif catalyzes the oxidation of methane to methanol which is further transformed to formaldehyde and formic acid as is demonstrated using13CH4and18O labelling. (FePctBu4)2N - H2O2system shows a high activity in the oxidation of benzene to phenol which occurs via formation of benzene oxide and exhibits NIH shift typically accociated with biological oxidation. Mechanistic features of oxidation of methane and benzene as well as detected intermediate hydroperoxo- and high valent oxo diiron complexes support an O-atom transfer reaction mechanism relevant to bio-oxidation.