Fe K-edge HERFD of biomimetic models of soluble methane monooxygenase intermediates P, P' and Q

The soluble methane monooxygenase P intermediate formed after O2 uptake is proposed to convert into the active Q via a transient protonated P’ species. Stable molecular models are valuable to establish spectroscopic and structural markers. A model for P comprising of a μ-1,2-peroxo diferric complex 1 was isolated, its one-electron oxidized product 2 and its protonated diferric product 3. While the current evidences support the μ-1,2-peroxo and μ-1,2-hydroperoxo motifs respectively, structural verification is lacking. The stability of 3 enabled the unprecedented isolation of a model for P’. Without stabilizing groups, a highly reactive model species 5 is formed, which is a model for Q. Fe K-edge Kα-HERFD XAS will provide us with the required sensitivity and selectivity to the samples’ signal to allow for establishing reference information on the electronic structure (from pre-edge features) and geometry (from EXAFS) of functional models of all sMMO intermediates.