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Fast Hydrogen Atom Abstraction by a Hydroxo Iron(III) Porphyrazine.

ABSTRACT: A reactive hydroxoferric porphyrazine complex, [(PyPz)FeIII(OH) (OH2)]4+ (1, PyPz = tetramethyl-2,3-pyridino porphyrazine), has been prepared via one-electron oxidation of the corresponding ferrous species [(PyPz)FeII(OH2)2]4+ (2). Electrochemical analysis revealed a pH-dependent and remarkably high FeIII-OH/FeII-OH2 reduction potential of 680 mV vs Ag/AgCl at pH 5.2. Nernstian behavior from pH 2 to pH 8 indicates a one-proton, one-electron interconversion throughout that range. The O-H bond dissociation energy of the FeII-OH2 complex was estimated to be 84 kcal mol-1. Accordingly, 1 reacts rapidly with a panel of substrates via C-H hydrogen atom transfer (HAT), reducing 1 to [(PyPz)FeII(OH2)2]4+ (2). The second-order rate constant for the reaction of [(PyPz)FeIII(OH) (OH2)]4+ with xanthene was 2.22 × 103 M-1 s-1, 5-6 orders of magnitude faster than other reported FeIII-OH complexes and faster than many ferryl complexes.

SUBMITTER: Gao H

PROVIDER: S-EPMC6036922 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature

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Fast Hydrogen Atom Abstraction by a Hydroxo Iron(III) Porphyrazine.

Gao Hongxin H Groves John T JT

Journal of the American Chemical Society 20170308 11

A reactive hydroxoferric porphyrazine complex, [(PyPz)FeIII(OH) (OH2)]4+ (1, PyPz = tetramethyl-2,3-pyridino porphyrazine), has been prepared via one-electron oxidation of the corresponding ferrous species [(PyPz)FeII(OH2)2]4+ (2). Electrochemical analysis revealed a pH-dependent and remarkably high FeIII-OH/FeII-OH2 reduction potential of 680 mV vs Ag/AgCl at pH 5.2. Nernstian behavior ...[more]

PMID: 28245648

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