Small Molecule Models for Nonporphyrinic Iron and Manganese Oxygenases

Acid‐Triggered O−O Bond Heterolysis of a Nonheme FeIII(OOH) Species for the Stereospecific Hydroxylation of Strong C−H Bonds

“…[13,40,41] This formulation fully agreedw ith high-resolution cryospraym asss pectrometric (CSI-MS) analyses conducted at À40 8C. UV/Vis absorption spectral monitoring of this process showed the formation of ab and at 514 nm (e = 1600 m À1 cm À1 ,d etermined on the basis of the double integrationoft he EPR signal, see below) within 250 seconds (Figure1a).…”

“…[7,8] Event hought he Fe III (OO(H)) moiety is the last detected speciesb efore substrate oxidation occurs, an intense debate exists on whether this species is directly responsible for the reactivity [9,10] or merely ap recursort oamore reactive high-valent oxoiron speciesg enerated after homolytic or heterolytic OÀOb ond cleavage, for example,Fe IV (O)/HO··or Fe V (O)/HO À respectively. Typically these speciesr esult from the reaction of an iron(II) precursor with excess hydrogen peroxide at low temperatures, [13,14] but in selected examples, they are generated by ac ombination of O 2 and ar educing agent. Typically these speciesr esult from the reaction of an iron(II) precursor with excess hydrogen peroxide at low temperatures, [13,14] but in selected examples, they are generated by ac ombination of O 2 and ar educing agent.…”

Evidence for an oxygen evolving iron–oxo–cerium intermediate in iron-catalysed water oxidation

“…In this context, the study of the water oxidation (WO) reaction with chemical oxidants catalysed by well-defined coordination complexes can clarify fundamental principles underlying the mechanisms of O-O bond formation and cleavage 12,13 , the latter being at the heart of chemical processes by which aerobic organisms respire 14 . Most remarkably, given the strong parallels between the oxidation chemistry of iron and manganese compounds 15 , it can be envisioned that fundamental chemical insights extracted from studies of O-O bond formation by iron coordination compounds can shed light on intermediates and mechanisms operating at the Oxygen Evolving Complex (OEC).…”

Non‐Heme Imine‐Based Iron Complexes as Catalysts for Oxidative Processes

“…[67] Higher KIE values, from about 3u pt o4-5, have been measured for selective, metal-based oxidants. [13,41,51,61,68,69] Va lues higher than the theoretical maximum (ca. 7) have been determined in some casesa nd rationalized on the basis of the contributiono ft unneling effects.I t has to be remarked that KIE analysisg ives information only on the selectivity determining step as recently pointed out by Hartwig.…”

“…[77] On the other hand, for the active species of cytochrome P450 enzymes and other selectiveh emec atalysts,t he adamantane regioselectivity can achieve valuesa sh igh as 48. [42,68] Thus,w hile lowv alueso ft he tertiary to secondary ratio (38 8/28 8 < 6) are indicative of af ree-radical mechanism, 38 8/28 8 ratios higher than 13-15 strongly point to am etal-based mechanism.…”