Oxoferryl complexes of the halogenated (porphinato)iron catalyst [tetrakis(2,6-dichlorophenyl)porphinato]iron

Gold, Avram; Jayaraj, K.; Doppelt, P.; Weiss, R.; Chottard, Geneviève; Bill, Eckhard; Ding, Xiao‐Qi; Trautwein, A. X.

doi:10.1021/ja00225a028

Cited by 98 publications

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“…Table 1 summarizes the values in the literature and our results on a series of spectra from various complexes with different porphyrins, counter ions and solvents. The ferryl oxidation state of iron in these complexes is suggested from the isomer shifts which are consistent with published data on other complexes containing the [Fe0I3+ unit [l8, 27,32,[34][35][36][37][38][39].…”

Section: Mosshauer and Epr Spectroscopysupporting

confidence: 88%

“…Oxidation of the trifluoromethane sulfonato complex in this medium at -40 "C by a fourfold excess of m-chloroperoxybenzoic acid yielded a green compound having an ultraviolet/visible spectrum virtually identical to that of [ ] Additional evidence for the oxoferrylporphyrin cation radical structure of the oxidized dichlorophenyl-substituted complex was provided by the pathway of decay: at -4 0 T the green species initially formed decayed within 5 min to a red compound having a P-band at 560 nm, characteristic of the oxoferryl tetra(2,6-dichloropheny1)porphyrin. Such one-electron reduction to neutral oxoferryl complexes has been reported for a number of oxoferrylporphyrin cation radical systems [32]. Hence, the structural assignment [TPP(2,6-CI)Fe = O ] + ( O S 0 2 C F~) has been made to the green complex.…”

Section: Oxidution Reactionsmentioning

confidence: 74%

“…Techniques for obtaining ultraviolet/visible, 'H-NMR and Mossbauer samples have been described in detail elsewhere [32]. Samples for EPR spectroscopy were prepared with the methods used for the preparation of 'H-NMR probes.…”

Section: Ox Idu T Ionsmentioning

confidence: 99%

“…6) appears as a doublet, displaying pronounced line asymmetry, due to broadening by a weak internal field of 1-2 T. The reduction of the internal field in this compound by a factor of . [32], contamination by an uncoupled iron(1V) complex is plausible). All simulations are based on the spin Hamiltonian, Eqn (I), with parameters given in Table 2, and were performed in the slow relaxation limit.…”

Section: Mosshauer and Epr Spectroscopymentioning

confidence: 99%

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Evidence for variable metal‐radical spin coupling in oxoferrylporphyrin cation radical complexes

Bill

Ding

Bominaar

et al. 1990

European Journal of Biochemistry

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Oxoferrylporphyrin cation radical complexes were generated by m-chloroperoxybenzoic acid oxidation of the chloro and trifluoromethanesulfonato complexes of tetramesitylporphyrinatoiron(II1) [(TMP)Fe] and the trifluoromethanesulfonato complex of tetra(2,6-dichlorophenyl)porphyrinatoiron(IlI) [TPP(2,. Coupling between ferry1 iron (S = 1) and porphyrin radical (S' = 1/2) spin systems was investigated by Mossbauer and EPR spectroscopy. The oxoferrylporphyrin cation radical systems generated from the TMP complexes show strong ferromagnetic coupling. Analysis of the magnetic Mossbauer spectra, using a spin Hamiltonian explicitly including a coupling tensor J , suggests an exchange-coupling constant J > 80 cm-'. The EPR spectra show non-zero rhombicity, the origin of which is discussed in terms of contributions from the usual zero-field effects of iron and from iron-radical spin-dipolar interaction. A consistent estimate of zero-field splitting parameter D = + 6 cm-' was obtained by EPR and Mossbauer measurements. EPR and Mossbauer parameters are shown to be slightly dependent on solvent, but not on the axial ligand in the starting (TMP)Fe complex. In contrast to the TMP complex, the oxoferrylporphyrin cation radical system generated from [TPP(2,6-C1)FeOS02CF3] exhibits Mossbauer and EPR spectra consistent with weak iron-porphyrin radical coupling of IJI = 1 cm-'.High-valency oxoheme complexes, formally two-electron oxidized above the ferric state, have been of considerable interest because of their importance in the chemistry of catalase and peroxidase enzymes [l, 21 and because they play a putative role in monooxygen transfer to organic substrates by cytochrome P450 [3, 41. Efforts to model biochemical function and to characterize better the electronic structure of these intermediates have resulted in the synthesis of oxoheme complexes in the same oxidation state as the enzymatic transients [5, 61 and in mimicking some of the biochemical functions of cytochrome P450 [5 -151. The sum of the physicochemical evidence marshalled to date best describes the complexes as oxoferrylporphyrin cation radical complexes [5, 16 -291. Despite the potential importance of the synthetic complexes for the elucidation of the electronic structures of the biological transients, only the oxoferrylporphyrin cation radical system [(TMP)Fe = 0 1 +Cl-, derived from tetramesitylporphyrinatoiron(II1) chloride [(TMP)FeCl], has been the object of serious efforts at characterization (complexes like [(TMP)Fe = O](Cl-), the counter ions are written in parentheses to indicate uncertainty as to the exact nature of their association with the iron(1V) center}. A large variety of spectroscopic techniques has been used for investigation of this species [6,16,18, 231. Strong ferromagnetic coupling between the electron spins of iron and the tetramesitylporphyrin radical has been demonCorrespondenre to A.

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Section: Mosshauer and Epr Spectroscopysupporting

confidence: 88%

Section: Oxidution Reactionsmentioning

confidence: 74%

Section: Ox Idu T Ionsmentioning

confidence: 99%

Section: Mosshauer and Epr Spectroscopymentioning

confidence: 99%

See 2 more Smart Citations

Evidence for variable metal‐radical spin coupling in oxoferrylporphyrin cation radical complexes

Bill

Ding

Bominaar

et al. 1990

European Journal of Biochemistry

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“…(taml = tetraamido macrocyclic ligand) have DE Q values of 2.08 [9] and 3.3 mm s À1 . [10] Correlation of the Mössbauer data with the near-IR spectrum taken of the Mössbauer sample affords a molar extinction coefficient of 260 m À1 cm À1 for the 790-nm chromophore of 3.…”

Section: IVmentioning

confidence: 99%

Contrasting cis and trans Effects on the Reactivity of Nonheme Oxoiron(IV) Complexes

et al. 2008

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Position determines properties: The oxidative properties of [FeIV(O)(L)(X)] species (L=tetradentate N4 ligand, X=monodentate ligand) depend on the position of the X ligand. The FeO unit is a poorer oxidant with an electron‐donating cis ligand but becomes a much better oxidant when this ligand is trans to the oxo group. This difference in reactivity reflects perturbations to the electronic structure of the highly covalent FeO moiety.

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Iron Porphyrin Chemistry

Walker¹,

Simonis²

2005

Encyclopedia of Inorganic Chemistry

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This article reviews most aspects of the chemistry of iron porphyrins, from Fe(0) to Fe(V), including occurrence and roles of natural iron porphyrins (hemes) and their synthetic analogs, structures and electron configurations of iron porphyrins of all oxidation and spin states, π electron configuration of the porphyrin ring, synthesis of metal‐free porphyrins and other related macrocycles, insertion of iron into free‐base porphyrins and related macrocycles, the properties, reactions, uses and biological relevance of iron(0), ‐(I), ‐(II) porphyrins (the latter with S = 0, 1, and 2 spin state possibilities), of iron(II) porphyrin π‐cation radicals, of iron(III) porphyrins (with S = 1/2, 3/2, and 5/2 spin state possibilities), of iron(III) porphyrin and corrole π‐cation radicals, of iron(IV) porphyrins (including five‐ and six‐coordinate ferryl (FeO) 2+ , iron(IV) phenyl, carbene and hydrazine complexes, and the bis‐methoxide complex) and a comparison of iron(IV) porphyrins to iron(III) porphyrin π‐cation radicals, of iron(IV) porphyrin π‐cation radicals, and of the possible existence of iron(V) porphyrins. Included in the Fe(II) part are sections on addition of ligands to four‐coordinate iron(II) porphyrins, including equilibrium binding constants, photodissociation of ligands from PFeL 2 complexes, binding of small molecules (O 2 , CO, NO, HNO) to 5‐coordinate iron(II) porphyrins and design of porphyrin ligands that will mimic the active sites of heme proteins such as myoglobin and hemoglobin, the cytochromes P450 and nitric oxide synthases, and the nitrophorins and guanylyl cyclases. Included in the iron(III) part are sections on both 5‐ and 6‐coordinate high‐spin complexes and their similarities and differences, bridged or through‐space magnetically coupled complexes of high‐spin iron(III) porphyrins with other metal complexes as possible models for cytochrome oxidase and the assimilatory sulfite reductases, coupled oxidation of hemes by hydrogen peroxide or its equivalent, and the relationship of this reactivity to the reactions of heme oxygenase, iron(III) porphyrins as reduction catalysts, and photochemistry of iron(III) porphyrins, possible electron configurations of low‐spin iron(III) porphyrins, the phenomenon and possible electronic consequences of ruffling of the porphinato core in iron(III) porphyrins, the preferred orientation of planar axial ligands bound to low‐spin iron(III) porphyrins, NO complexes of iron(III) porphyrins, reduction potentials, equilibrium constants and rates of axial‐ligand addition and exchange, kinetics of axial‐ligand rotation and porphyrin ring inversion, kinetics of reduction and autoreduction of iron(III) porphyrins, electron self‐exchange between low‐spin iron(III) and iron(II) porphyrins, synthetic ferriheme proteins, and synthesis of five‐coordinate low‐spin iron(III) porphyrins having σ‐alkyl or σ‐aryl groups as axial ligands. The iron(IV) and iron(IV) cation radical sections discuss the high‐valent states of cytochromes P450 and related enzymes.

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Oxoferryl complexes of the halogenated (porphinato)iron catalyst [tetrakis(2,6-dichlorophenyl)porphinato]iron

Cited by 98 publications

References 0 publications

Evidence for variable metal‐radical spin coupling in oxoferrylporphyrin cation radical complexes

Evidence for variable metal‐radical spin coupling in oxoferrylporphyrin cation radical complexes

Contrasting cis and trans Effects on the Reactivity of Nonheme Oxoiron(IV) Complexes

Iron Porphyrin Chemistry

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