Activation of Dioxygen by a Mononuclear Nonheme Iron Complex: Sequential Peroxo, Oxo, and Hydroxo Intermediates
| Autor: | Kyle M. Lancaster, Samantha N. MacMillan, David P. Goldberg, Pierre Moënne-Loccoz, Avery C. Vilbert, Ida M. DiMucci, Jesse B. Gordon |
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| Rok vydání: | 2019 |
| Předmět: |
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Molecular Structure Chemistry Iron General Chemistry Ligands 010402 general chemistry 01 natural sciences Biochemistry Medicinal chemistry Article Catalysis Nonheme iron 0104 chemical sciences Oxygen X-Ray Absorption Spectroscopy Colloid and Surface Chemistry Models Chemical Coordination Complexes Oxidation-Reduction Density Functional Theory |
| Zdroj: | J Am Chem Soc |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/jacs.9b05274 |
| Popis: | The activation of dioxygen by Fe(II)(Me(3)TACN)(S(2)SiMe(2)) (1) is reported. Reaction of 1 with O(2) at −135 °C in 2-MeTHF generates a thiolate-ligated (peroxo)diiron complex Fe(III)(2)(O(2))(Me(3)TACN)(2)(S(2)SiMe(2))(2) (2) that was characterized by UV–vis (λ(max) = 300, 390, 530, 723 nm), Mössbauer (δ = 0.53, |ΔE(Q)| = 0.76 mm s(−1)), resonance Raman (RR) (ν(O–O) = 849 cm(−1)), and X-ray absorption (XAS) spectroscopies. Complex 2 is distinct from the outer-sphere oxidation product 1(ox) (UV–vis (λ(max) = 435, 520, 600 nm), Mössbauer (δ = 0.45, ΔE(Q) = 3.6 mm s(−1)), and EPR (S = 5/2, g = [6.38, 5.53, 1.99])), obtained by one-electron oxidation of 1. Cleavage of the peroxo O–O bond can be initiated either photochemically or thermally to produce a new species assigned as an Fe(IV)(O) complex, Fe(IV)(O)(Me(3)TACN)(S(2)SiMe(2)) (3), which was identified by UV–vis (λ(max) = 385, 460, 890 nm), Mössbauer (δ = 0.21, |ΔE(Q)| = 1.57 mm s(−1)), RR (ν(Fe(IV)=O) = 735 cm(−1)), and X-ray absorption spectroscopies, as well as reactivity patterns. Reaction of 3 at low temperature with H atom donors gives a new species, Fe(III)(OH)(Me(3)TACN)(S(2)SiMe(2)) (4). Complex 4 was independently synthesized from 1 by the stoichiometric addition of a one-electron oxidant and a hydroxide source. This work provides a rare example of dioxygen activation at a mononuclear nonheme iron(II) complex that produces both Fe(III)–O–O–Fe(III) and Fe(IV)(O) species in the same reaction with O(2). It also demonstrates the feasibility of forming Fe/O(2) intermediates with strongly donating sulfur ligands while avoiding immediate sulfur oxidation. |
| Databáze: | OpenAIRE |
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