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Issue 13, 2013
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Kinetic insights into the reactivity of the intermediates generated from hydrogen peroxide and diiron(III) complex with tris(picolyl)amine (TPA)

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Abstract

Two intermediates (2 and 3) are formed consecutively in the reaction of a diiron(III) complex [FeIII2(μ-O)(OH)(H2O)(TPA)2](ClO4)3 (TPA = tris(2-pyridylmethyl)amine, tris(picolyl)amine) with H2O2 in CH3CN at −40 °C. Low-temperature stopped-flow studies showed that both species are kinetically competent in oxidation of phosphines and phenols. The first intermediate (2) reacts with substrates very rapidly (second-order rate constants reach 105–106 M−1 s−1 for substituted triarylphosphines and 103–105 M−1 s−1 for substituted phenols), in keeping with a diiron(IV)–oxo formulation. The second intermediate (3), a mixed-valent Fe(III)Fe(IV) species, is more stable than 2, and reacts with substrates more slowly (second-order rate constants range from 150 to 550 M−1 s−1 for triaryl phosphine oxidation, and from 18 to 790 M−1 s−1 for phenol oxidation). Reaction rates increase with increasing electron donating abilities of substituents, indicating that both 2 and 3 act as electrophilic oxidants.

Graphical abstract: Kinetic insights into the reactivity of the intermediates generated from hydrogen peroxide and diiron(iii) complex with tris(picolyl)amine (TPA)

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Publication details

The article was received on 30 Oct 2012, accepted on 12 Dec 2012 and first published on 13 Dec 2012


Article type: Paper
DOI: 10.1039/C2DT32599C
Citation: Dalton Trans., 2013,42, 4427-4435
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    Kinetic insights into the reactivity of the intermediates generated from hydrogen peroxide and diiron(III) complex with tris(picolyl)amine (TPA)

    X. Sun, S. V. Kryatov and E. V. Rybak-Akimova, Dalton Trans., 2013, 42, 4427
    DOI: 10.1039/C2DT32599C

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