(TAML)FeIV=O complex in aqueous solution:: Synthesis and spectroscopic and computational characterization
(TAML)FeIV=O complex in aqueous solution:: Synthesis and spectroscopic and computational characterization
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DOI：
10.1021/ic7022902
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发表时间：
2008-05-05
影响因子：
4.6
通讯作者：
Bominaar, Emile L.
中科院分区：
文献类型：
--
作者：
Chanda, Arani;Shan, Xiaopeng;Bominaar, Emile L.
最近，我们报道了S = 1/2配合物[Fe-V（O）B*]（-）的表征，其中B* 属于四氨基大环配体（TAML）家族，其铁配合物活化过氧化物用于环境有用的应用。用叔丁基过氧化氢氧化[Fe-III（H2O）B*]（-）（1），在pH > 12的水溶液中，以>95%的产率制备了相应的单电子还原物种[Fe-IV（O）B *]（2-）（2）。在室温下，单体物质2与二聚体物质[B*Fe-IV-O-（Fe B）-B-IV*]（2-）（3）处于可逆的pH依赖性平衡，其中pK（a）接近10。在零场下，2的穆斯堡尔谱呈现出四极偶极子，Δ E-Q = 3.95（3）mm/s和Δ = -0.19（2）mm/s，参数与S = 1的Fe-IV态一致。在外加磁场中的研究得到零场分裂参数D = 24（3）cm（-1）和磁超精细张量A/g（n）beta（n）=（-27，-27，+2）T。2的Fe K边EXAFS分析显示在1.69（2）埃处有一个散射体，该距离与Fe-IV=O键一致。[Fe-IV（O）B ~*]（2-）的密度泛函理论计算与实验结果吻合得很好。通过引入轴向氧与两个溶剂-水分子的氢键，实现了进一步的显着改善。结果表明，配合物2的Fe-57超精细参数表明B ~* 对Fe有较强的电子贡献.
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.