Investigation of the EPR parameters and local structures for Cu2+ in Bis(l-asparaginato) M(II) catalysts (M=Zn, Cd, Mg)
Investigation of the EPR parameters and local structures for Cu2+ in Bis(l-asparaginato) M(II) catalysts (M=Zn, Cd, Mg)
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DOI：
10.1016/j.jpcs.2012.02.021
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发表时间：
2012-07
影响因子：
4
通讯作者：
Zhang Hua-ming;W. Shao-Yi;Kuang Min-Quan;Zhang Zhi-hong
中科院分区：
文献类型：
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作者：
Zhang Hua-ming;W. Shao-Yi;Kuang Min-Quan;Zhang Zhi-hong
利用正交细长八面体中3d9离子的高阶摄动公式，从理论上研究了双（l-天冬酰胺）M（II）催化剂（M=Zn, Cd, Mg）中Cu2+的电子顺磁共振参数（g因子和超精细结构常数）。考虑到强共价性，从聚类方法中考虑了配体轨道和自旋轨道耦合的贡献。发现配体八面体（即[CuO4N2]12−簇）由于Jahn-Teller效应和大小不匹配而经历轴向和垂直的局部键长变化Δ（≈0.19-0.25Å）和Δ（≈0.12-0.14Å），这与纯化合物中的宿主M2+位点不同。基于上述局部结构的理论EPR参数与观测值吻合较好，且与前人相比有一定的改进。讨论了这些中心的局部结构。
The electron paramagnetic resonance (EPR) parameters (g factors and hyperfine structure constants) for Cu2+in Bis(l-asparaginato) M(II) catalysts (M=Zn, Cd, Mg) are theoretically investigated using the high order perturbation formulas of these parameters for 3d9ions in orthorhombically elongated octahedra. Ligand orbital and spin–orbit coupling contributions are included from the cluster approach in view of strong covalency. The ligand octahedra (i.e., [CuO4N2]12−clusters) are found to experience axial and perpendicular local bond length variations Δ (≈0.19–0.25Å) and δ (≈0.12–0.14Å) due to the Jahn–Teller effect and size mismatch, which are dissimilar to those of host M2+sites in pure compounds. The theoretical EPR parameters based on the above local structures show good agreement with the observed values, and some improvements are achieved as compared with those in the previous work. The local structures of these centers are discussed.