(TAML)FeIV=O complex in aqueous solution:: Synthesis and spectroscopic and computational characterization

被引：110

作者：

Chanda, Arani ^{[2
]}

Shan, Xiaopeng ^{[1
,3
]}

Chakrabarti, Mrinmoy ^{[2
]}

Ellis, W. Chadwick ^{[2
]}

Popescu, Delia L. ^{[2
]}

de Oliveira, Filipe Tiago ^{[2
]}

Wang, Dong ^{[1
,3
]}

Que, Lawrence, Jr. ^{[1
,3
]}

Collins, Terrence J. ^{[2
]}

Munck, Eckard ^{[2
]}

Bominaar, Emile L. ^{[2
]}

机构：

[1] Univ Minnesota, Dept Chem, Minneapolis, MN 55455 USA

[2] Carnegie Mellon Univ, Dept Chem, Pittsburgh, PA 15213 USA

[3] Univ Minnesota, Ctr Met Biocatalysis, Minneapolis, MN 55455 USA

来源：

INORGANIC CHEMISTRY | 2008年 / 47卷 / 09期

关键词：

D O I：

10.1021/ic7022902

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

Recently, we reported the characterization of the S = 1/2 complex [Fe-V(O)B*](-), where B* belongs to a family of tetraamido macrocyclic ligands (TAMLs) whose iron complexes activate peroxides for environmentally useful applications. The corresponding one-electron reduced species, [Fe-IV(O)B*](2-) (2), has now been prepared in >95% yield in aqueous solution at pH > 12 by oxidation of [Fe-III(H2O)B*](-) (1), with tert-butyl hydroperoxide. At room temperature, the monomeric species 2 is in a reversible, pH-dependent equilibrium with dimeric species [B*Fe-IV-O-(FeB)-B-IV*](2-) (3), with a pK(a) near 10. In zero field, the Mossbauer spectrum of 2 exhibits a quadrupole doublet with Delta E-Q = 3.95(3) mm/s and delta = -0.19(2) mm/s, parameters consistent with a S = 1 Fe-IV state. Studies in applied magnetic fields yielded the zero-field splitting parameter D = 24(3) cm(-1) together with the magnetic hyperfine tensor A/g(n)beta(n) = (-27, -27, +2) T. Fe K-edge EXAFS analysis of 2 shows a scatterer at 1.69 (2) angstrom, a distance consistent with a Fe-IV=O bond. DFT calculations for [Fe-IV(O)B*](2-) reproduce the experimental data quite well. Further significant improvement was achieved by introducing hydrogen bonding of the axial oxygen with two solvent-water molecules. It is shown, using DFT, that the Fe-57 hyperfine parameters of complex 2 give evidence for strong electron donation from B* to iron.

引用

页码：3669 / 3678

页数：10

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