The siting of Cu(II) in mordenite: a theoretical spectroscopic study
The siting of Cu(II) in mordenite: a theoretical spectroscopic study
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DOI：
10.1039/b105799p
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发表时间：
2002-01-01
影响因子：
3.3
通讯作者：
Schoonheydt, RA
中科院分区：
文献类型：
--
作者：
Delabie, A;Pierloot, K;Schoonheydt, RA
用大团簇模型从头计算方法研究了丝光沸石中Cu（II）的位置，该模型代表丝光沸石中的阳离子交换中心。部分几何优化，基于密度泛函理论（DFT），进行获得的结构的Cu（II）的配位环境在不同的网站。用多组态微扰理论（CASPT 2）计算了这些团簇的配位场谱和EPR g张量。计算结果与实验信息进行了比较，通过漫反射光谱（DRS）和EPR。计算表明，在低交换水平的Cu（II）是协调的丝光沸石的主通道中的氧六环，在两个铝的存在下。在较高的负载量下，仅含有一个铝的六环或五环也被占据，其中Cu（II）作为单个离子配位，而不是作为（CuOH）（+）。计算还表明，在完全脱水的丝光沸石，扭曲的八环（网站A）是不被占用的Cu（II）。
The siting of Cu(II) in mordenite has been studied by ab initio calculations on large cluster models, representing the cation exchange sites in mordenite. Partial geometry optimizations, based on density functional theory (DFT), were performed to obtain the structure of the coordination environment of Cu(II) at the different sites. The ligand field spectra and EPR g-tensors of these clusters were then calculated by means of multiconfigurational perturbation theory (CASPT2). The calculated results were compared with experimental information, obtained by diffuse reflectance spectroscopy (DRS) and EPR. The calculations indicate that at low exchange levels Cu( II) is coordinated to oxygen six-rings in the main channel of mordenite, in the presence of two aluminiums. At higher loadings, six- or five-rings containing only one aluminium also become occupied, where Cu(II) is coordinated as a single ion, not as (CuOH)(+). The calculations indicate also that in fully dehydrated mordenite, the twisted eight-ring (site A) is not occupied by Cu(II).