Tetra porphyrin iron

Luz et al. have proposed the combination of an iron-porphyrin (iron(m) tetra-(iV-methyl-4-pyridyl)-porphyrin noted as FeT4MPyP) co-adsorbed with MWCNTs on BPPG electrode for the electrocatalysis of GSH oxidation in phosphate buffer (pH 7.4). In comparison to bare BBPG or BBPG modified with either FeT4MPyP or MWCNTs only, the hybrid FeT4MPyP/MWCNT electrode exhibits improved catalytic effect in terms of overpotential and of catalytic current intensity (Fig. 19). 

BetteUieim A, Parash R, Ozer D. 1982. Catalysis of oxygen cathodic reduction by adsorbed iron(in)-tetra(A,A,A-trimethylanilinium)porphyrin on glassy carbon electrodes. J Electrochem Soc 129 2247. 

Shi C, Anson EC. 1990. Catalytic pathways for the electroreduction of oxygen by iron tetra-kis(4-iV-methylpyridyl)porphyrin or iron tetraphenylporphyrin adsorbed on edge plane pyrol3dic graphite electrodes. Inorg Chem 29 4298. 

The reduction electrochemistry of ECP porphyrin films furthermore responds to added axial ligands in the expected ways. We have tested this (2,6) for the ECP form of the iron complex of tetra(o-amino)phenyl)porphyrin by adding chloride and various nitrogeneous bases to the contacting solutions, observing the Fe(III/II) wave shift to expected potentials based on the monomer behavior in solution. This is additional evidence that the essential porphyrin structure is preserved during the oxidation of the monomer and its incorporation into a polymeric film. 

Manganese nitrosyl porphyrins [215] are considered good models for the iron-nitric oxide analogs, which are relatively unstable but very vital to many biological operations. A six-coordinate manganese nitrosyl porphyrin of the form (por)Mn(NO)(L), where por can be TTP (TTP = tetra(4-methylphenyl)porphine) and L = piperidine, methanol, 1-methyhmidazole, has been prepared [216] in moderate yields by the reductive nitrosylation of the (por)MnCl complex with NO in piperidine. The crystal structures of these compounds give indication of a linear Mn-NO bond [215]. 

With regard to the pressure effects, we have, as usual, been interested in systems that are not simple. One system we have been looking at involves water-soluble porphyrins. Actually, the only reactions we have studied thus far involve the iron(III) and manganese(III) tetra(4-N-methylpyridyl)porphyrin complexes. These complexes are in the form of tosylate salts, which causes some problems. The rate constants are on the order... 

Reduction of p-oxo-bis[tetraphenylporphin iron(iii)] with sodium amalgam gives several products sequentially. The first reduction product is the radical-anion [(tpp)Fe ] , which has a spin state of - at 77 K and at 300 K. This is the first reported study of an Fe -porphyrin.Mossbauer data on a range of tetra-aryl-substituted iron-porphines and their p-oxo-bridged derivatives have been reported. A crystallographic study on bis(imidazole) otPy -tetraphenylporphinatoiron(iii) chloride-methanol solvate shows the [FeN ] core to be quasitetragonal. An n.m.r. study has been made of the related... 

Cyclic voltammetry of iron(III) porphyrin-sulfate complexes has been described. Thiosulfate can add to iron(III) porphyrins to give an adduct which is high-spin at normal temperatures but low-spin at low temperatures. The tetraphenylporphyrin adduct undergoes decomposition slowly in DMF to give [Fe (tpp)] plus tetrathionate. In DMSO tetraphenylporphyrinatoiron(III) oxidizes thiosulfate by an autocatalytic process. Tetrathiotungstate complexes of iron(III)-tetra-phenylporphyrin undergo spontaneous reduction to iron(II) products with a half-life of about 30 minutes at ambient temperature. " ... 

Porphycenes (150) and corrphycenes (151) are porphyrin isomers, several of whose iron(III) complexes have been characterized. Examples include distorted square-pyramidal (12,17-diethox-ycarbonyl-2,3,6,7,1 l,18-hexamethylcorrphycenato)iodo-iron(III), [Fe(tprpc)X] (where tprpc = 2,7, 12,17-tetra-u-propylporphycene) with X = C1, Br, N3, 02CMe, or OPh and [Fe(tprpc)2]0. " Iron(II)- and iron(IV)-tproc complexes also exist, as established in an examination of oxygenation of iron(II) porphycene.The structure of chloro(3,6,13,16-tetraethyl-2,7,12,17-tetramethylpor-phycenato)iron(III), also distorted square-pyramidal, has been compared with those of chloro-iron(III) porphyrin complexes. ... 

Fel3, first isolated in the pure state as recently as 1988 as a black, fairly stable solid (though unstable in solution), reacts with iodide to give the previously characterized complex [Fel4]. Iodide appears stable coordinated to iron(III) in ternary porphyrin complexes such as (12,17-diethoxycarbonyl-2,3,6,7,ll,18-hexamethylcorrphycenato)-iodo-iron(III), where Fe — I = 2.600 A, though it is oxidized by the mono-oxidized form of /.t-oxo-di-iron(III) bis-tetra-phenylporphyrin. " Remarkably, iodide has been reported coordinated to iron(V), in [Fe(313)I]. ... 

Fig. 5. Preparation of an iron(IV)oxo porphyrin radical cation bold lines, refer to meso-tetra mesityl porphine...

In order to compare chiral recognition of the substrate p-chlorostyrene in the presence of chiral picket fences and basket handles carrying the same amino acids the porphyrins 167-169 were prepared in a straightforward manner from the known a,j8,a,j -tetra(o-aminophenyl)porphyrin 170, Fig. 28 [113]. Reaction with t-butoxycarbonyl-L-phenylalanine, removal of the protecting group and subsequent condensation with terephthaloyl chloride e.g. furnished the free base of 169. Iron was always introduced using Fe(CO)5/I2 and the... 

The eclipsed tetra-BINAP porphyrin 171 was conveniently synthesized by condensation of the meso-tetrakis(2,6-dihydroxyphenyl)porphyrin 173 with the (S)-BINAP derivative 174 in the presence of K2C03. After removal of the staggered isomer iron was inserted by addition of Fe(CO)5/I2, and the resulting Fe(III)-complex 171 was used as a catalyst (0.2%) to epoxidize a series of six styrene derivatives in the presence of an excess of PhIO. In every case the corresponding (R)-epoxides were preferentially formed in yields up to 72%. The best ee-values were obtained for the electron deficient substrates 2-nitrostyrene (80% ee) and pentafluorostyrene (74% ee), [114],... 

An iron(III) porphyrin complex, (P8 )Fein(H20)2 (Px = tetra-ferf-butyl-tetrakis [2,2-bis(carboxylato)ethyl]-5,10,15,20-tetraphenylporphyrin), reacts reversibly with NO39 to form the nitrosyl complex. 

Treatment of TPPFe(III)Cl or raeso-tetra-o-tolylporphinato-iron(III) chloride [TTPFe(III)Cl (10)] with iodosylbenzene caused rapid oxidation of the porphyrin and loss of catalytic activity for hydrocarbon oxidation. Figure 1 shows changes in the visible absorption spectrum upon treatment of 10 with iodosylbenzene. These data indicate that shortly after the addition of iodosylbenzene (Scan b, Figure 1) a new porphyrin species (11) is formed, which then rapidly decays to oxidized porphyrin products. The kinetics of this decay process are approximately first order (Figure 2). 

Recently synthesized iron porphyrin-carbene complexes (136) may be considered as carbon analogues of the oxo-iron(IV) porphyrin (HRP-II and CAT-II) species.476 The one-electron oxidation of [Fe(TPP)(C=CR2)] (R = aryl) by CuCl2 affords the stable complex [Fe(TPP)(C=CR2)] Cl (TPP = wieso-tetra-p-tolyl porphyrin and R = p-ClC6H4) which has a visible spectrum very similar to that of CAT-I. X-Ray analysis of this complex has revealed a structure (137) in which the vinylidene moiety has inserted between the iron atom and one pyrrole ring of the porphyrin and it is suggested that this may constitute a model, i.e. structure (138), for the active site of CAT-I as an alternative to the Fe117 cation radical model.477... 

Iron tetra(p-methylpyridinium)porphyrin (T(p-M)PyP) Iron tetrakis(3-sulfonatophenyl)porphyrin (TPPS)... 

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