Oxygen-Bridged Iron-Copper Assemblies Pertinent to Heme-Copper Oxidases: Synthesis and Structure of an [FeIII-(OH)-CuII] Bridge and Exafs Multiple-Scattering Effects of Linear Oxo and Nonlinear Hydroxo Bridges
Oxygen-Bridged Iron-Copper Assemblies Pertinent to Heme-Copper Oxidases: Synthesis and Structure of an [FeIII-(OH)-CuII] Bridge and Exafs Multiple-Scattering Effects of Linear Oxo and Nonlinear Hydroxo Bridges
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DOI：
10.1021/ja00106a080
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发表时间：
1995-01
影响因子：
15
通讯作者：
M. J. Scott;H. Zhang;Sonny C. Lee;B. Hedman;K. Hodgson;R. H. Holm
中科院分区：
文献类型：
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作者：
M. J. Scott;H. Zhang;Sonny C. Lee;B. Hedman;K. Hodgson;R. H. Holm
最近，我们报告了成功使用 GNXAS 分析包来确定第一个协调球之外的可靠度量信息（包括角度）。当前特别相关的是，当反向散射和介入原子形成线性或近线性关系时，例如可能发生在[Fe-X-Cu]桥中，振幅显着增强。我们使用 GNXAS MS 协议分析 Fe K 边缘处的 (1)(ClO[sub 4]) 和 (3)(ClO[sub 4]) EXAFS 数据。给出了数据和数据拟合的 EXAFS 傅里叶变换 (FT)。两种配合物的拟合包括双体贡献 Fe-O、Fe-N 和 Fe-C[sub α] 以及三体 MS 成分 Fe-N-C[sub β]、Fe-O-Cu 和 Fe-N-C[sub γ]。线性 (1) 和非线性 (3) 的桥梁结构差异导致其 EXAFS 光谱发生巨大变化。 GNXAS 分析可有效量化 MS 信号对金属中心之间桥接结构几何形状的敏感性。如此处和相关案例所示，当电桥接近线性时，该技术相对灵敏且准确。然而，在基于血红素的 Fe-X-Cu 桥接组件中，卟啉 MS 效应对 Cu EXAFS 没有贡献。 15 个参考文献，2 个图。
Recently, we have reported the successful use of the GNXAS analysis package to determine reliable metric information (including angles) beyond the first coordination sphere. Of particular present relevance is the significant amplitude enhancement when a backscatter and an intervening atom form a linear or near-linear relationship, such as might occur in an [Fe-X-Cu] bridge. We have used the GNXAS MS protocol to analyze EXAFS data of (1)(ClO[sub 4]) and (3)(ClO[sub 4]) at the Fe K-edge. The EXAFS Fourier transforms (FTs) of the data and of the fit to the data are presented. The fits of both complexes include the two-body contributions Fe-O, Fe-N, and Fe-C[sub [alpha]] and the three-body MS components Fe-N-C[sub [beta]], Fe-O-Cu, and Fe-N-C[sub [gamma]]. The bridge structural differences in linear (1) and nonlinear (3) give rise to dramatic changes in their EXAFS spectra. GNXAS analysis is effective in quantifying the sensitivity of the MS signals to the geometry of the bridging configuration between metal centers. As shown here and for a related case, this technique is relatively sensitive and accurate when the bridge approaches linearity. However, in heme-based Fe-X-Cu bridged assemblies, porphyrin MS effects do not contribute to the Cu EXAFS. 15 refs., 2 figs.