Correlating Magnetic Exchange in Dinuclear Bis(phenolate)-Bridged Complexes: A Computational Perspective
Correlating Magnetic Exchange in Dinuclear Bis(phenolate)-Bridged Complexes: A Computational Perspective
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DOI：
10.1246/bcsj.20160077
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发表时间：
2016-06-15
影响因子：
4
通讯作者：
Hada, Masahiko
中科院分区：
文献类型：
--
作者：
Archana, Velloth;Imamura, Yutaka;Hada, Masahiko
采用密度泛函理论（DFT）方法研究了双核镍-镍和铜-铜双酚根桥联反铁磁金属配合物的磁性.两种铜配合物的偶合常数J分别为-384.8和-375.3cm（-1），镍配合物的偶合常数J为-85.7cm（-1），与实验值一致。重叠积分分析可以解释Ni和Cu配合物之间J耦合的差异：Cu配合物的两个d（x2-y2）轨道与酚盐配体位于同一平面，因此产生较强的J耦合，而Ni配合物的两个d（x2-y2）轨道由于Ni原子周围的不对称环境而偏离酚盐配体平面，产生中等的J耦合。我们还研究了几个重要的几何参数的磁相互作用的依赖性。M-O-M键角是反铁磁转变的关键参数，这与前人对其他配合物的研究结果一致。此外，增加M-O-O-M二面角，减小M-O-M键角和大的铰链扭曲这些复合物有效地增强铁磁交换，这是一个更好的分子磁体所需的条件。
Density functional theory (DFT) calculations were performed to analyse the magnetic properties of dinuclear Ni-Ni and Cu-Cu bis(phenolate)-bridged complexes with two anti-ferromagnetically-coupled metals. The estimated coupling constants J are -384.8 and -375.3 cm(-1) for the two Cu complexes and -85.7 cm(-1) for the Ni complex, which are consistent with the experimental values. Analysis of overlap integral can explain the difference in the coupling J between Ni and Cu complexes: Two d(x2-y2) orbitals of the copper complexes are located on the same plane as that of a phenolate ligand, and therefore produce the strong J coupling, whereas those of the nickel complex are tilted from the plane of phenolate ligand because of asymmetric environment around Ni atom, and produce moderate J coupling. We also examined the dependences of magnetic interaction in terms of several important geometrical parameters. The M-O-M bond angle is the key parameter for antiferro-ferromagnetic transition, which is consistent with previous studies for the other complexes. Also, increasing the M-O-O-M dihedral angle, decreasing the M-O-M bond angle and large hinge distortions on these complexes effectively enhance the ferromagnetic exchange, which is a desired condition for a better molecular magnet.