title: Million-fold activation of the [Fe(2)(micro-O)(2)] diamond core for C-H bond cleavage.
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 [Fe(2)(micro-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 [Fe(3.5)(micro-O)(2)Fe(3.5)](3+) diamond core (1) into a complex with a valence-localized [HO-Fe(III)-O-Fe(IV)=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) Fe(IV)=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.
authors.affiliation: Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Genqiang
authors.initials: G
authors.lastname: Xue
authors.forename: Raymond
authors.initials: R
authors.lastname: De Hont
authors.forename: Eckard
authors.initials: E
authors.lastname: Münck
authors.forename: Lawrence
authors.initials: L
authors.lastname: Que
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D006859:Hydrogen / Q000737:chemistry*; D058085:Iron Compounds / Q000737:chemistry*; D007536:Isomerism; D015394:Molecular Structure; D010084:Oxidation-Reduction
chemical_list: D058085:Iron Compounds; D002244:Carbon; D006859:Hydrogen