Issue 3, 2012

Mechanistic investigation of cyclohexane oxidation by a non-heme iron complex: evidence of product inhibition by UV/vis stopped-flow studies

Abstract

We report herein studies examining a binuclear non-heme iron model complex that is capable of catalytically oxidizing cyclohexane to cyclohexanol in excess of 200 turnovers, relative to the iron complex, and cyclohexanone (5 turnovers) via heterolytic cleavage of the mechanistic probe peroxide MPPH. Low-temperature stopped-flow electronic spectroscopy was utilized to investigate the mechanism of the reaction of this diiron(II) compound, Fe2(H2Hbamb)2(N-MeIm)2, (H2Hbamb = 2,3-bis(2-hydroxybenzamido)dimethylbutane) (1) with MPPH. In the absence of substrates, the reaction proceeds in three consecutive steps starting with oxygen atom transfer to the diferrous complex to generate a putative [FeIV[double bond, length as m-dash]O species], thought to be the oxidant in the catalytic cycle. Over time, the rate of catalysis is observed to decrease without consumption of all available peroxide. By utilizing low-temperature stopped-flow UV/vis kinetic studies, the diferrous complex, 1, is shown to undergo product inhibition arising from the interaction of either cyclohexanol or MPP-OL product species to the diiron center, therefore precluding further reaction with MPPH.

Graphical abstract: Mechanistic investigation of cyclohexane oxidation by a non-heme iron complex: evidence of product inhibition by UV/vis stopped-flow studies

Supplementary files

Article information

Article type
Paper
Submitted
28 Sep 2011
Accepted
01 Oct 2011
First published
22 Nov 2011

Dalton Trans., 2012,41, 777-782

Mechanistic investigation of cyclohexane oxidation by a non-heme iron complex: evidence of product inhibition by UV/vis stopped-flow studies

L. C. Gregor, G. T. Rowe, E. Rybak-Akimova and J. P. Caradonna, Dalton Trans., 2012, 41, 777 DOI: 10.1039/C1DT11841B

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