28755-93-3Relevant articles and documents
A convenient procedure for the synthesis of fluoro-iron(III) complexes of common synthetic porphyrinates
Meininger, Daniel J.,Muzquiz, Nicanor,Arman, Hadi D.,Tonzetich, Zachary J.
, p. 416 - 423 (2014)
We report here an improved method for the preparation of fluoro-iron(III) porphyrinate complexes. Treatment of [Fe2(P)2(μ-O)] (P = tetraphenylporphyrinate {TPP}, tetra-p-tolylporphyrinate {TTP}, or octaethylporphyrinate {OEP}) or [Fe(OH)(OH2)(TMP)] (TMP = tetramesitylporphyrinate) with the commercially available fluorinating agent, Et3N·3HF, in dichloromethane affords the desired [FeF(P)] complexes in a straightforward fashion and in good yield while avoiding the use of aqueous hydrofluoric acid. All fluoro-iron(III) complexes have been completely characterized by a series of different spectroscopic techniques including cyclic voltammetry. Reaction of a representative complex, [FeF(OEP)], with various chloride reagents demonstrates that halide exchange with chloride is facile, but only proceeds at an appreciable rate in the presence of proton sources. Unexpectedly, treatment of [FeF(OEP)] with NOBF4 did not to lead formation of an oxidized species, but rather to formation of the {Fe-NO}6 complex, [Fe(NO)(OEP)](BF4).
Low-Temperature EPR Studies of Highly Anisotropic Low-Spin (Protoporphyrinato)iron(III) Complexes
Migita, Catharina T.,Iwaizumi, Masamoto
, p. 4378 - 4381 (1981)
Low-spin complexes of ferric protoporphyrin IX showing highly anisotropic EPR spectra (HALS) have been investigated by systematically changing the axial bases.From EPR measurements at low temperatures, complete sets of principal g values were obtained for a series of these complexes.The cubic field strength and tetragonal splitting in these HALS complexes appear to be smaller than those of ordinary low-spin complexes (LS).Interestingly, the tetragonal splitting of HALS complexes decreases with an increase of the axial field strength, in contrast to that of LS complexes where the tetragonal splitting increases with an increase of the axial field strength.From an analysis of the ligand field parameters obtained from the HALS complexes it has been suggested that the ferric ions in the HALS complexes may be a little displaced from the porphyrin plane and also that the HALS state may be close to the spin-crossover point between the intermediate-spin and the high-spin states.
Iodo(etiohemiporphycenato)iron(III). Unexpected difference in magnetic behavior in solution and solid
Ohgo, Yoshiki,Neya, Saburo,Takahashi, Masashi,Takeda, Masuo,Funasaki, Noriaki,Nakamura, Mikio
, p. 526 - 527 (2003)
Although iodo(etiohemiporphycenato)iron(III) showed an admixed intermediate-spin state (S = 3/2, 5/2) with a major contribution of S = 3/2 in solution, the same complex exhibited the high-spin state (S = 5/2) in the solid phase. Importance of the crystal packing has been pointed out for the formation of the high-spin complex in the solid.
Synthesis and structural determination of new octaethylporphyrin iron(III) complexes containing cyanamide derivatives as axial ligand
Khorasani-Motlagh, Mozhgan,Safari, Nasser,Noroozifar, Meissam,Shahroosvand, Hashem,Patrick, Brian O.
, p. 1260 - 1266 (2009/06/05)
The reactions of heme, [OEPFeCl] where OEP is the dianion of octaethylporphyrin, with phenylcyanamide (pcyd) ligands have been studied. Four new porphyrin complexes, [OEPFe(L)] (L = pcyd (2), 2-Clpcyd (3), 2-Mepcyd (4), 2,4-Me2pcyd (5)), have b
Electroreduction of μ-oxo iron(III) porphyrins adsorbed on an electrode leading to a cofacial geometry for the iron(II) complex: Unexpected active site for the catalytic reduction of O2 to H2O
Oyaizu, Kenichi,Haryono, Agus,Natori, Junichiro,Shinoda, Hiroshi,Tsuchida, Eishun
, p. 1153 - 1163 (2007/10/03)
Acidification of a solution of (μ-oxo)bis[(5,10,15,20- tetraphenylporphyrinato)iron(III)] ([{Fe(tpp)}2O], II) in CH2Cl2 produced equimolar amounts of a hydroxoiron(III) complex [(tpp)Fe(III)(OH)] (III) and an iron(III) complex [(tpp)Fe(III)(ClO4)] (IV). The complex IV was isolated as a perchlorate salt, which crystallized in the triclinic space group P1 (2); a = 11.909(3), b = 19.603(4), c = 10.494(3) A, α = 95.74(2)°, β = 107.91(2)°, γ = 89.14(2)°, V = 2319.1(9) A3, Z = 2, D(calc)= 1.328 g cm-3, μ(Mo Kα) = 4.35 cm-1, final R = 0.055 and R(w) = 0.050. The crystal structure of IV revealed that ClO4- is coordinated to the iron atom, which may be driven by the preference of iron(III) to be five coordinate rather than four coordinate. Reduction of the complex II in the presence of acid by electrolysis and/or by a reducing agent, such as sodium dithionite, under argon produced [Fe(II)(tpp)]. The addition of O2 to a solution of [Fe(tpp)] in acidic CH2Cl2 in the presence of an equimolar amount of the reducing agent produced the complex III. When the complex II was adsorbed on an electrode surface and placed in aqueous acidic electrolyte solutions, electroreduction of the adsorbate proceeded according to the half- reaction: [{Fe(tpp)}2O] +2H++2e-→2[Fe(tpp)]+H2O, at 0.031-0.059 pH V (vs. SCE, pH > 1.0). Based on these results, oxo-bridged iron(III) porphyrin dimers were used as electrocatalysts for the reduction of O2. The catalytic reduction of O2 proceeded at potentials in the vicinity of those for II. As a whole, the proportion of H2O as the product increased from 50% for adsorbed [(tpp)Fe(III)Cl] to > 90% for the adsorbed dimer. Thus, electroreduction of the dimer adsorbed on a carbon electrode immersed in aqueous acid produced two solid state, cofacially fixed iron(II) porphyrin molecules: [PFe(III)OFe(III)P](ad)+2H++2e-→[PFe(II) Fe(II)P](ad)+H2O (P = porphyrin dianion). Coordination of molecular oxygen to the adjacent two iron(II) centers under acidic conditions allowed formation of O2-bridged iron(III) porphyrin [PFe(III)(O2) Fe(III)P](ad) at the electrode surface. Electroreduction of the adsorbate under acidic conditions produced H2O and allowed the reformation of [PFe(II) Fe(II)P](ad). The implication is that the electroreduction of the adsorbed oxo-bridged dimer gives a cofacial geometry for PFe(II) on the electrode, facilitating the coordination and subsequent splitting of O2.
In situ monitoring of the degradation of iron porphyrins by dioxygen with hydrazine as sacrificial reductant. Detection of paramagnetic intermediates in the coupled oxidation process by1H NMR spectroscopy
Balch, Alan L.
, p. 684 - 691 (2008/10/08)
The effects of using hydrazine rather than ascorbic acid on the coupled oxidation of (OEP)FeII(py)2 (OEP is the dianion of octaethylporphyrin, py is pyridine) have been investigated with the goal of directly detecting reactive intermediates during the process of heme degradation by dioxygen. The reaction products, [(OEOP)FeII(py)2]Cl and (OEB)FeIII(py)2 (OEOP is the monoanion of octaethyl-5-oxaporphyrin and OEB is the trianion of octaethylbilindione), and their yields are similar to those of the standard coupled oxidation process. The reaction has been monitored in situ in pyridine/dichloromethane mixtures by 1H NMR spectroscopy. The recently isolated and crystallographically characterized complex, (OEPO)Fe(py)2 (OEOP is the trianion of octaethyloxaphlorin), has been identified as a key intermediate. Addition of dioxygen to (OEP)FeII(py)2 in pyridine with hydrazine present also produces two new transient species: (OEPO)Fe(py)(N2D4) and (OEPO)Fe(N2D4)2. These complexes have also be produced independently by low-temperature titration of hydrazine into a solution of {(OEPO)Fe}2. Thus, hydrazine acts as an axial ligand during the early stages of the coupled oxidation process. However, the two hydrazine-containing complexes eventually are converted into (OEPO)Fe(py)2 before [(OEOP)FeII(py)2]Cl and (OEB)FeIII(py)2 are formed. The observations reported here suggest that the coupled oxidation process can be divided into two stages. The first stage involves the meso C-H bond and results in introduction of oxygen at that site with the formation of the three intermediates: (OEPO)Fe(N2H4)2, (OEPO)Fe(N2H2)(py), and (OEPO)Fe(py)2. The second stage of the coupled oxidation process involves C-C bond breaking and the conversion of the hydroxylated heme, (OEPO)Fe(py)2, into the final products, [(OEOP)FeII(py)2]+ and (OEB)FeIII(py)2.
Oxochromium compounds. 1. Synthesis and properties of μ-oxo chromium-iron porphyrin and phthalocyanine compounds
Liston, David J.,Kennedy, Brendan J.,Murray, Keith S.,West, Bruce O.
, p. 1561 - 1567 (2008/10/08)
The reaction between CrIVO(P) and FeII(P′) leads to the formation of μ-oxo heterobinuclear complexes (P)CrOFe(P′) where P and P′ represent dianions of porphyrins that may be the same or different. [Abbreviations for the dianions of 5,10,15,20-tetraarylporphyrins: TPP, tetraphenylporphyrin; TTP, tetra-p-tolylporphyrin; TMP, tetrakis(p-methoxyphenyl)porphyrin; TFP, tetrakis(p-fluorophenyl)porphyrin; TCP, tetrakis(p-chlorophenyl)porphyrin; TXP, tetra-3,5-xylylporphyrin; OEP, the dianion of 2,3,7,8,12,13,17,18-octaethylporphyrin; Pc, the dianion of the phthalocyanine molecule.] The complexes react with heterocyclic Lewis bases, and these coordinate to Cr only. The visible, infrared, 1H NMR, and Mo?ssbauer spectra are reported for the compounds. The variation of magnetic susceptibility with temperature down to 4.2 K is interpreted in terms of strong antiferromagnetic coupling between Cr(III) (S = 3/2) and Fe(III) (S = 5/2) centers with J values in the range -130 to -150 cm-1. Zero field splitting effects are important at low temperatures. The reaction of CrO(TPP) with FeII(Pc) forms an analogous μ-oxo complex having porphyrin and phthalocyanine groups attached to Cr(III) and Fe(III), respectively.
SYNTHESES AND MAGNETIC PROPERTIES OF ARYLIRON(III) COMPLEXES OF OCTAETHYLPORPHYRINS
Ogoshi, Hisanobu,Sugimoto, Hiroshi,Yoshida, Zen-Ichi,Kabayashi, Hanako,Sakai, Hiroshi,Maeda, Yutaka
, p. 185 - 196 (2007/10/02)
Aryliron(III) octaethylporphyrins, OEP-FeIII(4-XC6H4) were obtained from octaethylporphyrinatoiron(III) perchlorate, OEP-FeIII(ClO4) and arylmagnesium bromides.In order to confirm the ESR parameters, the
