期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2003
卷号：100
期号：7
页码：3665-3670
DOI：10.1073/pnas.0636830100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The reaction of [FeII(tris(2-pyridylmethyl)amine, TPA)(NCCH3)2]2+ with 1 equiv. peracetic acid in CH3CN at -40{degrees}C results in the nearly quantitative formation of a pale green intermediate with {lambda}max at 724 nm ({varepsilon} {approx} 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 Mossbauer spectra recorded in zero field reveal a doublet with {Delta}EQ = 0.92(2) mm/s and {delta} = 0.01(2) mm/s; analysis of spectra obtained in strong magnetic fields yields parameters characteristic of S = 1 FeIV[IMG]/medium/dbond_large.gif" ALT="Formula ">O complexes. The presence of an FeIV[IMG]/medium/dbond_large.gif" ALT="Formula ">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 A to fit the extended x-ray absorption fine structure region. The [FeIV(O)(TPA)]2+ intermediate is stable at -40{degrees}C for several days but decays quantitatively on warming to [Fe2({micro}-O)({micro}-OAc)(TPA)2]3+. Addition of thioanisole or cyclooctene at -40{degrees}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[IMG]/medium/dbond_large.gif" ALT="Formula ">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[IMG]/medium/dbond_large.gif" ALT="Formula ">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.
