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

doi:10.1021/ic001300k

A mechanistic study of the reaction between a diiron(II) complex [Fe^II₂(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

Chemistry (Twin Cities)

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48 Scopus citations

Abstract

A kinetic study of the reaction between a diiron(II) complex [Fe^II₂(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 [Fe^III₂(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 [Fe^II₂] 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 Fe^IIFe^III species is a likely steady-state intermediate during the oxygenation of complex 1.

Original language	English (US)
Pages (from-to)	2220-2228
Number of pages	9
Journal	Inorganic Chemistry
Volume	40
Issue number	10
DOIs	https://doi.org/10.1021/ic001300k
State	Published - May 7 2001

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@article{7f73d68f83734e89a96e3b0ab3356dc0,

title = "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",

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.",

author = "Kryatov, {S. V.} and Rybak-Akimova, {E. V.} and MacMurdo, {V. L.} and Jr Que",

year = "2001",

month = may,

day = "7",

doi = "10.1021/ic001300k",

language = "English (US)",

volume = "40",

pages = "2220--2228",

journal = "Inorganic Chemistry",

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publisher = "American Chemical Society",

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TY - JOUR

T1 - 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

AU - Kryatov, S. V.

AU - Rybak-Akimova, E. V.

AU - MacMurdo, V. L.

AU - Que, Jr

PY - 2001/5/7

Y1 - 2001/5/7

N2 - 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.

AB - 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.

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