Chemical Plausibility of Cu(III) with Biological Ligation in pMMO

Abstract

The mechanisms of dioxygen activation and methane C−H oxidation in particulate methane monooxygenase (pMMO) are currently unknown. Recent studies support a binuclear copper site as the catalytic center. We report the low-temperature assembly of a high-valent dicopper­(III) bis­(μ-oxide) complex bearing marked structural fidelity to the proposed active site of pMMO. This unprecedented dioxygen-bonded Cu­(III) species with exclusive biological ligation directly informs on the chemical plausibility and thermodynamic stability of the bis­(μ-oxide) structure in such dicopper sites and foretells unusual optical signatures of an oxygenation product in pMMO. Though the ultimate pMMO active oxidant is still debated, C–H oxidation of exogenous substrates is observed with the reported Cu­(III) complexes. The assembly of a high valent species both narrows the search for relevant pMMO intermediates and provides evidence to substantiate the role of Cu­(III) in biological redox processes