title: Structural insights into nonheme alkylperoxoiron(III) and oxoiron(IV) intermediates by X-ray absorption spectroscopy.
abstract: Transient mononuclear low-spin alkylperoxoiron(III) and oxoiron(IV) complexes that are relevant to the activation of dioxygen by nonheme iron enzymes have been generated from synthetic iron(II) complexes of neutral tetradentate (TPA) and pentadentate (N4Py, Bn-TPEN) ligands and structurally characterized by means of Fe K-edge X-ray absorption spectroscopy (XAS). Notable features obtained from fits of the EXAFS region are Fe-O bond lengths of 1.78 A for the alkylperoxoiron(III) intermediates and 1.65-1.68 A for the oxoiron(IV) intermediates, reflecting different strengths in the Fe-O pi interactions. These differences are also observed in the intensities of the 1s-to-3d transitions in the XANES region, which increase from 4 units for the nearly octahedral iron(II) precursor to 9-15 units for the alkylperoxoiron(III) intermediates to 25-29 units for the oxoiron(IV) species.
authors.affiliation: Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455, USA.
authors.forename: Jan-Uwe
authors.initials: JU
authors.lastname: Rohde
authors.forename: Stéphane
authors.initials: S
authors.lastname: Torelli
authors.forename: Xiaopeng
authors.initials: X
authors.lastname: Shan
authors.forename: Mi Hee
authors.initials: MH
authors.lastname: Lim
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Klinker
authors.forename: József
authors.initials: J
authors.lastname: Kaizer
authors.forename: Kui
authors.initials: K
authors.lastname: Chen
authors.forename: Wonwoo
authors.initials: W
authors.lastname: Nam
authors.forename: Lawrence
authors.initials: L
authors.lastname: Que
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry / Q000378:metabolism; D005583:Fourier Analysis; D058085:Iron Compounds / Q000737:chemistry*; D008958:Models, Molecular; D019159:Nonheme Iron Proteins / Q000737:chemistry* / Q000378:metabolism; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D010545:Peroxides / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D013056:Spectrophotometry, Ultraviolet
chemical_list: D058085:Iron Compounds; D019159:Nonheme Iron Proteins; D010545:Peroxides; D010100:Oxygen