Characterization and Properties of Non-Heme Iron Peroxo Complexes

Girerd, Jean‐Jacques; Banse, Frédéric; Simaan, A. Jalila

doi:10.1007/3-540-46592-8_6

Cited by 154 publications

(194 citation statements)

References 62 publications

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“…5, 6. 3,38 However, independence of k obs on iron concentration was observed for the decay of the TPA-supported alkylperoxoiron(III) intermediate in acetone at −50 °C and for the decay of the BPMCNsupported alkylperoxoiron(III) intermediate in CH 2 Cl 2 at −67 °C (see Table S1 in Supporting Information), thereby supporting the validity of eqn 4. Figure 1) and low-spin iron(III) EPR and Raman spectra (Table 2, Figure S5), analogous to those reported previously for [Fe II (TPA)(OO t Bu)(NCMe)] 2+ in CH 3 CN (vide infra).…”

Section: General Remarksmentioning

confidence: 68%

Kinetic Analysis of the Conversion of Nonheme (Alkylperoxo)iron(III) Species to Iron(IV) Complexes

et al. 2007

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Low-spin mononuclear alkylperoxoiron(III) complexes decompose by peroxide O-O bond homolysis to form iron(IV) species. We examined the kinetics of previously reported homolysis reactions for alkylperoxoiron(III) intermediates supported by TPA (tris-(2-pyridylmethyl)amine) in CH 3 CN solution and promoted by pyridine-N-oxide, by BPMCN (N,N-bis(2-pyridylmethyl)-N,Ndimethyl-trans-1,2-diaminocyclohexane) in its cis-β configuration in CH 3 CN and CH 2 Cl 2 , as well as for the previously unreported chemistry of TPA and 5-Me 3 TPA intermediates in acetone. Each of these reactions forms an oxoiron(IV) complex, except for the β-BPMCN reaction in CH 2 Cl 2 that yields a novel (hydroxo)alkylperoxoiron(IV) product. Temperature-dependent rate measurements suggest a common reaction trajectory for each of these reactions, and verify previous theoretical estimates of a ca. 60 kJ/mole enthalpic barrier to homolysis. However, both the tetradentate supporting ligand and exogenous ligands in the sixth octahedral coordination site significantly perturb the homolyses, such that observed rates can vary over two orders of magnitude at a given temperature. This is manifested as a compensation effect in which increasing activation enthalpy is offset by increasingly favorable activation entropy. Moreover, the applied kinetic model is consistent with geometric isomerism in the low-spin alkylperoxoiron(III) intermediates, wherein the alkylperoxo ligand is coordinated in either of the inequivalent cis sites afforded by the non-heme ligands.

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Section: General Remarksmentioning

confidence: 68%

Kinetic Analysis of the Conversion of Nonheme (Alkylperoxo)iron(III) Species to Iron(IV) Complexes

et al. 2007

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“…The absolute g values are represented in Figure 6 case is frequently encountered in LS heme systems, [11] whereas the negative value of D' case occurs in non-heme Fe III A C H T U N G T R E N N U N G (OOH) model complexes. [3] In this latter case, which is of interest here and which will be dealt with in the rest of the paper, all of the g values are positive.…”

Section: Discussionmentioning

confidence: 96%

“…[2] Intensive studies have been dedicated to modeling these intermediates, and we [3] and others [4] have been able to prepare and identify synthetic non-heme Fe III A C H T U N G T R E N N U N G (OOH) complexes. In general, these intermediates are obtained by the addition of H 2 O 2 to Fe II complexes prepared with hexa-, penta-, and tetradendate aminopyridine ligands (see Scheme 1) [3,4] and have been characterized by several techniques, in particular, EPR and resonance Raman spectroscopy. Apart from two cases, [5,6] Fe III A C H T U N G T R E N N U N G (OOH) species exhibit LS Fe III EPR features and their vibrational characteristics indicate an end-on coordination mode for the hydroperoxo ligand.…”

Section: Introductionmentioning

confidence: 99%

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Preparation and Characterization of a Microcrystalline Non‐Heme Fe^III(OOH) Complex Powder: EPR Reinvestigation of Fe^III(OOH) Complexes—Improvement of the Perturbation Equations for the g Tensor of Low‐Spin Fe^III

Martinho¹,

Dorlet²,

Rivière³

et al. 2008

Chemistry A European J

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The first example of a microcrystalline powder of a synthetic low-spin (LS) mononuclear Fe(III)(OOH) intermediate has been obtained by the precipitation of the [Fe(III)(L(5) (2))(OOH)](2+) complex at low temperature. The high purity of this thermally unstable powder is revealed by magnetic susceptibility measurements. EPR studies on this complex, in the solid state and also in frozen solution, are reported and reveal the coexistence of two related Fe(III)(OOH) species in both states. We also present a theoretical analysis of the g tensor for LS Fe(III) complexes, based on new perturbation equations. These simple equations provide distortion-energy parameters that are in good agreement with those obtained by a full-diagonalization calculation.

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“…The structure and properties of a diversity of complexes with the general structure (LM) n -O 2 (n = 1, 2) have been described. [2,3,[6][7][8][9][10][11][12] LM-O 2 adducts present usually end-on or side-on coordination modes (see Scheme 1) and can react to give (LM) 2 -O 2 binuclear complexes, or LM-O 2 -L'M' when two different metal centers are involved, where the most frequent coordination modes are mh 2 :h 2 -O 2 in many Cu complexes, [2,11] bis(m-O) in Cu, [2,11] Mn, [13][14][15][16][17] Scheme 1. Metal-O 2 coordination modes.…”

Section: Introductionmentioning

confidence: 98%

On the Reaction Mechanism of the Complete Intermolecular O₂ Transfer between Mononuclear Nickel and Manganese Complexes with Macrocyclic Ligands

Zapata-Rivera¹,

Caballol²,

Calzado³

et al. 2014

Chemistry A European J

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The recently described intermolecular O2 transfer between the side-on Ni-O2 complex [(12-TMC)Ni-O2](+) and the manganese complex [(14-TMC)Mn](2+), where 12-TMC and 14-TMC are 12- and 14-membered macrocyclic ligands, 12-TMC=1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane and 14-TMC=1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, is studied by means of DFT methods. B3LYP calculations including long-range corrections and solvent effects are performed to elucidate the mechanism. The potential energy surfaces (PESs) compatible with different electronic states of the reactants have been analyzed. The calculations confirm a two-step reaction, with a first rate-determining bimolecular step and predict the exothermic character of the global process. The relative stability of the products and the reverse barrier are in line with the fact that no reverse reaction is experimentally observed. An intermediate with a μ-η(1):η(1)-O2 coordination and two transition states are identified on the triplet PES, slightly below the corresponding stationary points of the quintet PES, suggesting an intersystem crossing before the first transition state. The calculated activation parameters and the relative energies of the two transition sates and the products are in very good agreement with the experimental data. The calculations suggest that a superoxide anion is transferred during the reaction.

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Characterization and Properties of Non-Heme Iron Peroxo Complexes

Cited by 154 publications

References 62 publications

Kinetic Analysis of the Conversion of Nonheme (Alkylperoxo)iron(III) Species to Iron(IV) Complexes

Kinetic Analysis of the Conversion of Nonheme (Alkylperoxo)iron(III) Species to Iron(IV) Complexes

Preparation and Characterization of a Microcrystalline Non‐Heme Fe^III(OOH) Complex Powder: EPR Reinvestigation of Fe^III(OOH) Complexes—Improvement of the Perturbation Equations for the g Tensor of Low‐Spin Fe^III

On the Reaction Mechanism of the Complete Intermolecular O₂ Transfer between Mononuclear Nickel and Manganese Complexes with Macrocyclic Ligands

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Characterization and Properties of Non-Heme Iron Peroxo Complexes

Cited by 154 publications

References 62 publications

Kinetic Analysis of the Conversion of Nonheme (Alkylperoxo)iron(III) Species to Iron(IV) Complexes

Kinetic Analysis of the Conversion of Nonheme (Alkylperoxo)iron(III) Species to Iron(IV) Complexes

Preparation and Characterization of a Microcrystalline Non‐Heme FeIII(OOH) Complex Powder: EPR Reinvestigation of FeIII(OOH) Complexes—Improvement of the Perturbation Equations for the g Tensor of Low‐Spin FeIII

On the Reaction Mechanism of the Complete Intermolecular O2 Transfer between Mononuclear Nickel and Manganese Complexes with Macrocyclic Ligands

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Preparation and Characterization of a Microcrystalline Non‐Heme Fe^III(OOH) Complex Powder: EPR Reinvestigation of Fe^III(OOH) Complexes—Improvement of the Perturbation Equations for the g Tensor of Low‐Spin Fe^III

On the Reaction Mechanism of the Complete Intermolecular O₂ Transfer between Mononuclear Nickel and Manganese Complexes with Macrocyclic Ligands