An N-bridged high-valent diiron–oxo species on a porphyrin platform that can oxidize methane

Abstract

High-valent oxo–metal complexes are involved in key biochemical processes of selective oxidation and removal of xenobiotics. The catalytic properties of cytochrome P-450 and soluble methane monooxygenase enzymes are associated with oxo species on mononuclear iron haem and diiron non-haem platforms, respectively. Bio-inspired chemical systems that can reproduce the fascinating ability of these enzymes to oxidize the strongest C–H bonds are the focus of intense scrutiny. In this context, the development of highly oxidizing diiron macrocyclic catalysts requires a structural determination of the elusive active species and elucidation of the reaction mechanism. Here we report the preparation of an Fe(IV)(µ-nitrido)Fe(IV) = O tetraphenylporphyrin cation radical species at −90 °C, characterized by ultraviolet–visible, electron paramagnetic resonance and Mössbauer spectroscopies and by electrospray ionization mass spectrometry. This species exhibits a very high activity for oxygen-atom transfer towards alkanes, including methane. These findings provide a foundation on which to develop efficient and clean oxidation processes, in particular transformations of the strongest C–H bonds. A short-lived diiron–oxo species — based on a nitrido-bridged bis-porphyrin 1 1platform — capable of efficiently oxidizing the strongest of C–H bonds has been prepared and spectroscopically characterized. The catalytic properties of this high-valent diiron(IV)–oxo complex were elucidated by studying the oxidation kinetics of a range of alkanes.

Cite this article

Kudrik, E., Afanasiev, P., Alvarez, L. et al. An N-bridged high-valent diiron–oxo species on a porphyrin platform that can oxidize methane. Nature Chem 4, 1024–1029 (2012). https://doi.org/10.1038/nchem.1471

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