Author: ["Genqiang Xue","Raymond De Hont","Eckard Münck","Lawrence Que Jr"]
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Abstract
In biological systems, the cleavage of strong C–H bonds is often carried out by iron centres—such as that of methane monooxygenase in methane hydroxylation—through dioxygen activation mechanisms. High valent species with [Fe2(µ-O)2] diamond cores are thought to act as the oxidizing moieties, but the synthesis of complexes that cleave strong C–H bonds efficiently has remained a challenge. We report here the conversion of a synthetic complex with a valence-delocalized [Fe3.5(µ-O)2Fe3.5]3+ diamond core (1) into a complex with a valence-localized [HO–FeIII–O–FeIV=O]2+ open core (4), which cleaves C–H bonds over a million-fold faster. This activity enhancement results from three factors: the formation of a terminal oxoiron(iv) moiety, the conversion of the low-spin (S = 1) FeIV=O centre to a high-spin (S = 2) centre, and the concentration of the oxidizing capability to the active terminal oxoiron(iv) moiety. This suggests that similar isomerization strategies might be used by nonhaem diiron enzymes. Although enzymes are known to use diiron centres to cleave carbon–hydrogen bonds, preparing synthetic compounds that can break these strong, stable bonds has remained notoriously difficult. Now, converting a low-spin ‘diamond core’ iron–oxo biomimetic complex into its high-spin ‘open core’ counterpart has enhanced its C–H bond cleavage ability by over a million times. Cite this article
Xue, G., De Hont, R., Münck, E. et al. Million-fold activation of the [Fe2(µ-O)2] diamond core for C–H bond cleavage. Nature Chem 2, 400–405 (2010). https://doi.org/10.1038/nchem.586 