Kinetic Studies of Reactions of Dioxygen with Carboxylate-Bridged Diiron(II) Complexes Leading to the Formation of (μ-Oxo)diiron(III) Complexes

Stopped-flow kinetic studies of the reactions of [Fe2(BIPhMe)2(O2CH)4] (1a), where BIPhMe = 2,2‘-bis(1-methylimidazolyl)phenylmethoxymethane, and [Fe2(OH)(Me3TACN)2(OAc)2]+ (2a), where TACN = 1,4,7-trimethyl-1,4,7-triazacyclononane, with O2 are presented. In CHCl3, both reactions are first-order in...

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Bibliographic Details
Published in:Journal of the American Chemical Society 1997-01, Vol.119 (2), p.334-342
Main Authors: Feig, Andrew L, Masschelein, Axel, Bakac, Andreja, Lippard, Stephen J
Format: Article
Language:English
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Summary:Stopped-flow kinetic studies of the reactions of [Fe2(BIPhMe)2(O2CH)4] (1a), where BIPhMe = 2,2‘-bis(1-methylimidazolyl)phenylmethoxymethane, and [Fe2(OH)(Me3TACN)2(OAc)2]+ (2a), where TACN = 1,4,7-trimethyl-1,4,7-triazacyclononane, with O2 are presented. In CHCl3, both reactions are first-order in [O2] and second-order in diiron(II) complex concentration. Mechanisms consistent with the kinetic data are proposed. The main feature of these schemes is a bimolecular pathway involving a tetranuclear (μ4-peroxo)diiron(II)diiron(III) species in the transition state. Evidence for carboxylate shifts in the oxidation mechanisms is presented, offering one possible way in which this class of structural equilibria might control the chemistry at related non-heme diiron centers in metalloproteins.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja962814e