Ferromagnetic coupling in oximato-bridged multi-decker Ni(II) clusters.
Ferromagnetic coupling in oximato-bridged multi-decker Ni(II) clusters.
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DOI：
10.1039/c0dt00528b
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发表时间：
2010-10
影响因子：
4
通讯作者：
H. Kou;Guang-yu An;Cong-Min Ji;Bingwu Wang;A. Cui
中科院分区：
文献类型：
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作者：
H. Kou;Guang-yu An;Cong-Min Ji;Bingwu Wang;A. Cui
合成并表征了基于吡啶-2-酰胺肟的单层、双层和三层氧桥联的Ni(II)簇合物。四核阳离子单元[Ni(4)(Hpyaox)(2)(Pyaox)(2)](2+)稳定存在于反应溶液中。磁性研究表明，在磁性耦合常数(J)为0.66.3 cm(-1)(H=-2Js(Ni1)S(Ni2))的化合物中，相邻的Ni(II)离子之间通过肟桥发生了罕见的铁磁交换。密度泛函理论(DFT)计算和实验数据都证实了桥肟基的N-O键距在磁耦合中起决定性作用。对于目前的Ni(II)物种，N-O键距的延长导致了从反铁磁交换到铁磁交换的转变，临界键距为1.394ó。
Single-, double- and triple-decker oximato-bridged Ni(ii) clusters based on pyridine-2-amidoxime (H(2)pyaox) have been synthesized and characterized. The decks have the same tetranuclear cationic units [Ni(4)(Hpyaox)(2)(pyaox)(2)](2+) that are stably present in the reaction solution. Magnetic studies show that uncommon ferromagnetic exchange between the adjacent Ni(ii) ions through the oxime bridges is operative in the compounds with the magnetic coupling constant (J) in the range 0.6-6.3 cm(-1) (H = -2JS(Ni1)S(Ni2)). Density function theoretical (DFT) calculations and the experimental data confirm that the N-O bond distances of the bridging oxime group have a decisive effect in magnetic coupling. For the present Ni(ii) species, the elongation of N-O bond distances are responsible for the switching from antiferromagnetic to ferromagnetic exchange with the critical bond distance of 1.394 Å.