One-electron oxidation of nickel porphyrins: effect of structure and medium on formation of nickel(III) porphyrin or nickel(II) porphyrin .pi.-radical cation

Nahor, Gad S.; Neta, P.; Hambright, Peter; Robinson, L. R.

doi:10.1021/j100164a046

Cited by 27 publications

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“…The stability of the metal-oxidized nickel porphycene is remarkable, since oxidation of nickel(II)−porphyrins by pulse radiolysis and γ-radiolysis resulted in the formation of transient Ni(III)−porphyrins or π-radical cations of nickel(II)−porphyrins. In all cases, however, the one-electron-oxidation products, whether Ni(II) π-radical cation or Ni(III), decayed to yield two-electron ring oxidation products 9a…”

Section: Resultsmentioning

confidence: 96%

One-Electron Oxidation of Metalloporphycenes As Studied by Radiolytic Methods

et al. 1996

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One-electron and two-electron oxidations of 2,7,12,17-tetrapropylporphycene (H 2 TPrPc) and its Fe, Co, Ni, Cu, and Sn complexes in CH 2 Cl 2 , CCl 4 , and 2-PrOH solutions have been studied by radiolytic techniques. Formation and decay of intermediates formed upon one-electron oxidation have been followed by kinetic spectrophotometric pulse radiolysis, and the absorption spectra of stable oxidation products have been recorded following γ-radiolysis. H 2 TPrPc is oxidized to the π-radical cation and then to the dication, which is stable in aprotic solvents but is transformed to a different product in 2-PrOH. Similar oxidation to the π-radical cation and then to the dication was observed for the Cu II , Sn IV , Co III , and Fe III porphycenes. Co II and Ni II porphycenes underwent radiolytic oxidation to form stable Co III and Ni III products. The stability of the latter is in contrast with previous electrochemical observations, and the difference is ascribed to the effect of the axial ligand.

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Section: Resultsmentioning

confidence: 96%

One-Electron Oxidation of Metalloporphycenes As Studied by Radiolytic Methods

et al. 1996

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“…( )-Acid Solvolysis Kinetics. The kinetics of the acidinduced removal of Zn(II) from the water-soluble compounds at / = 0.50 (HCl/LiCl) were followed spectrophotometrically at 25 °C. In all cases the reactions were First order in porphyrin and second order in (H+) concentration.…”

Section: Resultsmentioning

confidence: 99%

Kinetic and equilibrium studies on porphyrins, chlorins, and isobacteriochlorins: basicities, zinc incorporation, and acid-catalyzed solvolysis reactions in aqueous and nonaqueous solutions

Sutter¹,

Hambright²

1992

Inorg. Chem.

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“…The potential oxidizing power of alkyl halide peroxy radicals and their abilities to oxidize MTPPʼs have been known from pulse radiolysis [19] as well as ESR [18] studies. An alkyl halide peroxy radical (RXOO • ) is formed when an alkyl halide radical ( • RX) reacts with molecular oxygen.…”

Section: Discussionmentioning

confidence: 99%

Photooxidation of cobalt(II)meso-tetraphenylporphyrin by p-benzoquinone and its mechanism studied by optical absorption and resonance Raman spectroscopies

Thanga

Verma

2003

J. Porphyrins Phthalocyanines

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Laser excitation of Co II TPP within the Soret absorption band in the presence of pbenzoquinone (p-BQ) results in oxidation of the complex. Oxidation occurs both at the metal center and the porphyrin ring depending upon the experimental conditions. Under anaerobic conditions, oxidation takes place at the metal center to produce the cobaltic species Co III (TPP) + , while in the presence of molecular oxygen oxidation also occurs at the porphyrin ring giving Co III (TPP) 2+• cation radical as oxidation product. From the inhibiting effect of peroxy radical trapping agent on the photooxidation of Co II TPP under aerobic conditions, the two-electron oxidation is suggested to involve solvent radicals and we discuss the mechanistic details of the process in this work.

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One-electron oxidation of nickel porphyrins: effect of structure and medium on formation of nickel(III) porphyrin or nickel(II) porphyrin .pi.-radical cation

Cited by 27 publications

References 0 publications

One-Electron Oxidation of Metalloporphycenes As Studied by Radiolytic Methods

One-Electron Oxidation of Metalloporphycenes As Studied by Radiolytic Methods

Kinetic and equilibrium studies on porphyrins, chlorins, and isobacteriochlorins: basicities, zinc incorporation, and acid-catalyzed solvolysis reactions in aqueous and nonaqueous solutions

Photooxidation of cobalt(II)meso-tetraphenylporphyrin by p-benzoquinone and its mechanism studied by optical absorption and resonance Raman spectroscopies

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