A mechanistic study of the reaction between a diiron(II) complex [FeII2(μ-OH)2(6-Me3-TPA) 2]2+ and O2 to form a diiron(III) peroxo complex

S. V. Kryatov, E. V. Rybak-Akimova, V. L. MacMurdo, Jr Que

Research output: Contribution to journalArticlepeer-review

48 Scopus citations

Abstract

A kinetic study of the reaction between a diiron(II) complex [FeII2(μ-OH)2(6-Me3-TPA) 2]2+ 1, where 6-Me3-TPA = tris(6-methyl-2-pyridylmethyl)amine, and dioxygen is presented. A diiron(III) peroxo complex [FeIII2(μ-O)-(μ-O2) (6-Me3-TPA)2]2+ 2 forms quantitatively in dichloromethane at temperatures from -80 to -40 °C. The reaction is first order in [FeII2] and [O2], with the activation parameters ΔH‡ = 17 ± 2 kJ mol-1 and ΔS‡ = -175 ± 20 J mol-1 K-1. The reaction rate is not significantly influenced by the addition of H2O or D2O. The reaction proceeds faster in more polar solvents (acetone and acetonitrile), but the yield of 2 is not quantitative in these solvents. Complex 1 reacts with NO at a rate about 103 faster than with O2. The mechanistic analysis suggests an associative rate-limiting step for the oxygenation of 1, similar to that for stearoyl-ACP Δ9-desaturase, but distinct from the probable dissociative pathway of methane monoxygenase. An η1-superoxo FeIIFeIII species is a likely steady-state intermediate during the oxygenation of complex 1.

Original languageEnglish (US)
Pages (from-to)2220-2228
Number of pages9
JournalInorganic Chemistry
Volume40
Issue number10
DOIs
StatePublished - May 7 2001

Fingerprint Dive into the research topics of 'A mechanistic study of the reaction between a diiron(II) complex [Fe<sup>II</sup><sub>2</sub>(μ-OH)<sub>2</sub>(6-Me<sub>3</sub>-TPA) <sub>2</sub>]<sup>2+</sup> and O<sub>2</sub> to form a diiron(III) peroxo complex'. Together they form a unique fingerprint.

Cite this