Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, Engesserstrasse 15, D-76131, Karlsruhe, Germany.
Inorg Chem. 2011 Nov 21;50(22):11604-11. doi: 10.1021/ic2015397. Epub 2011 Oct 24.
Two pairs of Ni(2)Dy(2) and Ni(2)Tb(2) complexes, [Ni(2)Ln(2)(L)(4)(NO(3))(2)(DMF)(2)] {Ln = Dy (1), Tb (2)} and [Ni(2)Ln(2)(L)(4)(NO(3))(2)(MeOH)(2)]·3MeOH {Ln = Dy (3), Tb (4)} (H(2)L is the Schiff base resulting from the condensation of o-vanillin and 2-aminophenol) possessing a defect-dicubane core topology were synthesized and characterized. All four complexes are ferromagnetically coupled, and the two Dy-analogues are found to be Single Molecule Magnets (SMMs) with energy barriers in the range 18-28 K. Compound 1 displays step-like hysteresis loops, confirming the SMM behavior. Although 1 and 3 show very similar structural topologies, the dynamic properties of 1 and 3 are different with blocking temperatures (3.2 and 4.2 K at a frequency of 1500 Hz) differing by 1 K. This appears to result from a change in orientation of the nitrate ligands on the Dy(III) ions, induced by changes in ligands on Ni(II).
合成并表征了两对 Ni(2)Dy(2) 和 Ni(2)Tb(2) 配合物，[Ni(2)Ln(2)(L)(4)(NO(3))(2)(DMF)(2)] {Ln = Dy (1), Tb (2)} 和 [Ni(2)Ln(2)(L)(4)(NO(3))(2)(MeOH)(2)]·3MeOH {Ln = Dy (3), Tb (4)}（H(2)L 是邻香草醛和 2-氨基酚缩合得到的希夫碱），它们具有缺陷二立方烷核心拓扑结构。所有四个配合物都是铁磁耦合的，两个 Dy 类似物被发现是单分子磁体（SMM），具有 18-28 K 范围内的能垒。化合物 1 显示出阶跃式磁滞回线，证实了 SMM 行为。尽管 1 和 3 具有非常相似的结构拓扑，但 1 和 3 的动力学性质不同，在 1500 Hz 的频率下，阻塞温度（分别为 3.2 和 4.2 K）相差 1 K。这似乎是由于 Ni(II)上配体的变化导致 Dy(III)离子上的硝酸盐配体的取向发生变化。
