Theoretical Investigation on the Mechanism of Oxygen Atom Transfer between Two Non‐Heme Iron Centres

Abstract

Density functional theory calculations are presented on the oxygen atom transfer reaction between two non‐heme iron centres: One contains Bn–tpen [N‐benzyl‐N,N′,N′‐tris(2‐pyridylmethyl)ethane‐1,2‐diamine], whereas the other contains N4Py [N,N‐bis(2‐pyridylmethyl)‐N‐bis(2‐pyridyl)methylamine]. The calculations show that the (Bn–tpen)Fe–O–Fe(N4Py) complex is a stable entity but considerably higher in energy than isolated species. However, a mechanism of oxygen atom transfer from one non‐heme iron centre to the other will proceed via this oxido‐bridged intermediate. This oxido‐bridged complex has both iron atoms in oxidation state III so that in the process of the formation of the complex, an electron transfer from the FeII centre to the FeIV(O) centre has taken place. Nevertheless, both metal atoms have different orbital and spin‐density occupation. A large solvent effect on the reaction barriers is obtained, indicating that the reaction proceeds only in very polar environments.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Oxygen Atom Transfer Reactions of Iridium and Osmium Complexes: Theoretical Study of Characteristic Features and Significantly Large Differences Between These Two Complexes

“…Oxygen atom transfer reactions mediated by transition metal complexes (eq ) are of considerable interest in synthetic and biomimetic chemistries. − M−O + normalR → normalM + normalO−R Because the oxygen atom is removed from metal center and added to substrate as shown in eq , this reaction deeply relates to catalytic oxygenation processes such as olefin epoxidation − and hydroxylation. − This process is also important in biological systems; actually a number of important metalloenzymes mediate atom transfer reaction as key step. , One of the typical examples is cytochrome P-450 class of enzymes. − Also, oxygen atom transfer reactions between nonheme iron-oxo and iron complexes are reported. − Another important example is activation of dioxygen molecule, − in which the O−O bond cleavage occurs and one of the two oxygen atoms is utilized for oxidation reaction via oxygen-atom transfer reaction.…”

“…To utilize effectively the oxygen atom transfer reaction in catalytic, biomimetic, and biological chemistries, correct knowledge of this reaction such as transition state geometry, its electronic structure, and determining factor of reactivity is indispensable. In this regard, several experimental and theoretical studies have been carried out to present such knowledge and clarify the determining factors so far. − …”

“…, 41, 1947 between nonheme iron-oxo and iron complexes are reported. [17][18][19][20] Another important example is activation of dioxygen molecule, [4][5][6] in which the O-O bond cleavage occurs and one of the two oxygen atoms is utilized for oxidation reaction via oxygen-atom transfer reaction.…”

Oxygen-atom transfer to a nucleophilic molybdenum complex

“…This reaction constitutes an interesting case for advanced theoretical calculations that would include spin-dependent energy surfaces. 31,32…”

Electronic Structure and Reactivity of Bioinspired Organometallic Iron Complexes Relevant to Small Molecule Activation

“…[72] Intermolecular OAT from one LFe IV =O species to L'Fe II via µ-oxoiron(III) dimers is used for comparison of their oxidizing power. [73,74] Many factors are known to have an influence on the reactivity of oxoiron(IV) species. For example, the role of the spin state in non-heme iron systems is currently under debate.…”