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An FeIV=O complex of a tetradentate tripodal nonheme ligand

Title
An FeIV=O complex of a tetradentate tripodal nonheme ligand
Authors
Hee Lim M.Rohde J.-U.Stubna A.Bukowski M.R.Costas M.Ho R.Y.N.Munck E.Nam W.Que Jr. L.
Ewha Authors
남원우
SCOPUS Author ID
남원우scopus
Issue Date
2003
Journal Title
Proceedings of the National Academy of Sciences of the United States of America
ISSN
0027-8424JCR Link
Citation
vol. 100, no. 7, pp. 3665 - 3670
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
The reaction of [FeII(tris(2-pyridylmethyl)amine, TPA)(NCCH3)2]2+ with 1 equiv. peracetic acid in CH3CN at -40°C results in the nearly quantitative formation of a pale green intermediate with γmax at 724 nm (ε ≈ 300 M-1·cm-1) formulated as [FeIV(O)(TPA)]2+ by a combination of spectroscopic techniques. Its electrospray mass spectrum shows a prominent feature at m/z 461, corresponding to the [FeIV(O)(TPA)(ClO4)]+ ion. The Mössbauer spectra recorded in zero field reveal a doublet with ΔEQ = 0.92(2) mm/s and δ = 0.01(2) mm/s; analysis of spectra obtained in strong magnetic fields yields parameters characteristic of S = 1 FeIV=O complexes. The presence of an FeIV=O unit is also indicated in its Fe K-edge x-ray absorption spectrum by an intense 1-s → 3-d transition and the requirement for an O/N scatterer at 1.67 Å to fit the extended x-ray absorption fine structure region. The [FeIV(O)(TPA)]2+intermediate is stable at -40°C for several days but decays quantitatively on warming to [Fe2(μ-O)(μ-OAc)(TPA)2]3+. Addition of thioanisole or cyclooctene at -40°C results in the formation of thioanisole oxide (100% yield) or cyclooctene oxide (30% yield), respectively; thus [FeIV(O)(TPA)]2+ is an effective oxygen-atom transfer agent. It is proposed that the FeIV=O species derives from O-O bond heterolysis of an unobserved FeII(TPA)-acyl peroxide complex. The characterization of [FeIV(O)(TPA)]2+ as having a reactive terminal FeIV=O unit in a nonheme ligand environment lends credence to the proposed participation of analogous species in the oxygen activation mechanisms of many mononuclear nonheme iron enzymes.
DOI
10.1073/pnas.0636830100
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자연과학대학 > 화학·나노과학전공 > Journal papers
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