Proton NMR investigation of iron(III) 5,10,15,20-tetrakis(2,6-disubstituted phenyl)porphyrins. Isolation and characterization of hydroxy-ligated (5,10,15,20-tetrakis(2,6-difluorophenyl)porphinato)iron(III)

Woon, T. C.; Shirazi, Ata; Bruice, Thomas C.

doi:10.1021/ic00241a029

Cited by 32 publications

(45 citation statements)

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“…46,47 Moreover, they introduce some crowding on the porphyrin faces and steric constraints about the meso-aryl C-C rotation. 35,[47][48][49][50] In order to ascertain the role of the porphyrin redox potentials in the observed processes, an electrochemical characterization was performed on 2H-TPyP, Zn-TPyP, the two models 2H-Ref and Zn-Ref, and two archetypal reference compounds, i.e. meso-tetraphenylporphyrin (2H-TPP) and Zn(II) mesotetraphenylporphyrin (Zn-TPP), in CH2Cl2.…”

Section: Resultsmentioning

confidence: 99%

Highlight on the solution processes occurring on silver(i)-assembling porphyrins in the presence of an excess of silver salt

et al. 2017

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Coordination cages obtained upon complexation of pyridyl functionalized porphyrins by Ag disassemble when overtaking a 1 : 2 stoichiometric amount of silver salt. An excess of Ag then leads to unusual chemical processes, here analyzed in detail, which permanently transform the monomeric porphyrins. The observed processes, discussed with reference to model compounds devoid of polyether substituted pyridyl residues, evidence a peculiar reactivity for meso 2,6-dimethylphenyl substituted porphyrins.

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Section: Resultsmentioning

confidence: 99%

Highlight on the solution processes occurring on silver(i)-assembling porphyrins in the presence of an excess of silver salt

et al. 2017

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“…The commercial porphyrin ligands 5,10,15,20tetrakis(2,6-dichlorophenyl)porphyrin, (TDCPP)H 2 , 5,10,15,20-tetrakis(2,6diflurophenyl)porphyrin, (TDFPP)H 2 , and 5,10,15,20-tetrakis(pentaflurophenyl)porphyrin, (TPFPP)H 2 were converted to the iron(III) hydroxide complexes (porph)Fe III (OH) (1) by literature methods. [21][22][23] We employed hydroxide complexes in this work so that ligand exchange reactions with water would not result in new species and because the hydroxide complexes are easier to oxidize than the corresponding chloride complexes.…”

Section: Resultsmentioning

confidence: 99%

“…Iron(III) hydroxy complexes (TDCPP)Fe III (OH) (1a), (TDFPP)Fe III (OH) (1b), and (TPFPP)Fe III (OH) (1c) were prepared by literature methods. [21][22][23] Commercial HPLC grade acetonitrile (99.9%) was distilled from P 2 O 5 prior to use. Commercial mchloroperoxybenzoic acid (MCPBA) (77%) was purified by crystallization from CH 2 Cl 2 and dried in vacuo.…”

Section: Experimental Section Materialsmentioning

confidence: 99%

Kinetics and Mechanism of Oxidation Reactions of Porphyrin−Iron(IV)−Oxo Intermediates

Pan

Newcomb

2007

Inorg. Chem.

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The kinetics of the reactions of three porphyrin-iron(IV)-oxo derivatives with alkenes and benzylic alcohols were measured. The iron-oxo systems studied were 5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin-iron(IV)-oxo (2a), 5,10,15,20-tetrakis(2,6-difluorophenyl)porphyrin-iron(IV)-oxo (2b), and 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin-iron(IV)-oxo (2c). Species 2 were stable for hours at room temperature as dilute solutions in acetonitrile and reacted hundreds to thousands of times faster in the presence of high concentrations of substrates. Typical second-order rate constants determined from pseudo-first-order kinetic studies are 1-2 x 10(-2) M(-1) s(-1) for reactions with styrene and 3 x 10(-2) M(-1) s(-1) for reactions with benzyl alcohol. The reactivity order for the iron-oxo species was 2a > 2b > 2c, which is inverted from that expected on the basis of the electron demand of the porphyrin macrocycles, and the oxidation reaction was suppressed when excess porphyrin-iron(III) complex was added to reaction mixtures. These observations indicate that the reactions involve disproportionation of the iron(IV)-oxo species 2 to give an iron(III) species and a more highly oxidized iron species, presumed to be an iron(IV)-oxo porphyrin radical cation, that is the true oxidant in the reactions. Analyses of the kinetics of oxidations of a series of para-substituted benzylic alcohols with Hammett sigma+ -substituent constants and with a dual-parameter method developed by Jiang (Jiang, X. K. Acc. Chem. Res. 1997, 30, 283) indicated that considerable positive charge developed on the benzylic carbons in the oxidation reactions, as expected for electrophilic oxidants, and also that substantial radical character developed on the benzyl carbon in the transition states.

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“…In the last two decades, a number of paramagnetic 1 H NMR studies have been reported on different iron(III) porphyrins. [10][11][12][13][31][32][33][34] The 1 H NMR spectra of 1, 2 and 3 are similar to those of high-spin iron(III) porphyrins previously studied, 13,[31][32][33][34] but certain differences in isotropic shifts and longitudinal relaxation times of the signals were observed. The larger isotropic shifts observed for the pyrrole protons in the iron(III) porphyrins of this work suggest a strong s-spin delocalization in the iron(III) d x 2 À y 2 orbital compared, for instance, with the unhindered iron(III) sulfonato porphyrin, (H 3 O) 3 Fe III (TPPS), and '' one-face ''-hindered iron(III) sulfonato porphyrin, Na 3 Fe III [e-HSP(C 12 )], in water.…”

Section: Temperature Dependence Of the Hyperfine-shifted Resonancesmentioning

confidence: 59%

1H-NMR spectroscopic studies of paramagnetic superstructured iron(III) porphyrinsThis article is dedicated to the memory of Professor Michel Momenteau of Institut Curie.Abbreviations. 1D and 2D: one-dimensional and two-dimensional; COSY: correlated spectroscopy; NOESY: nuclear Overhauser effect spectroscopy; TPP: 5,10,15,20-tetraphenylporphyrinate dianion.

2002

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Proton NMR investigation of iron(III) 5,10,15,20-tetrakis(2,6-disubstituted phenyl)porphyrins. Isolation and characterization of hydroxy-ligated (5,10,15,20-tetrakis(2,6-difluorophenyl)porphinato)iron(III)

Cited by 32 publications

References 0 publications

Highlight on the solution processes occurring on silver(i)-assembling porphyrins in the presence of an excess of silver salt

Highlight on the solution processes occurring on silver(i)-assembling porphyrins in the presence of an excess of silver salt

Kinetics and Mechanism of Oxidation Reactions of Porphyrin−Iron(IV)−Oxo Intermediates

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