Three tetranuclear copper(II)–lanthanide(III) complexes, [CuIILLnIII(o-van)(CH3COO)(MeOH)}2]·2H2O (LnIII = GdIII, TbIII, and DyIII), were synthesized and characterized, where H3L is 1-(2-hydroxybenzamido)-2-(2-hydroxy-3-methoxybenzylideneamino)ethane and o-van is 3-methoxysalicylaldehydato. These compounds are isomorphous to each other and consist of a cyclic tetranuclear CuII2LnIII2 structure, in which the CuII and LnIII ions are alternately arrayed and the CuII component complex. [CuIIL]− unit functions as a “bridging ligand-complex” between two adjacent LnIII ions through the phenolato and methoxy oxygen atoms at one side and the amido oxygen atom at the another side. The temperature-dependent magnetic susceptibilities from 2.0 to 300.0 K and the field-dependent magnetizations at 2.0 K from 0 to 5 T showed that the magnetic interaction between CuII and each of the lanthanide ions is ferromagnetic. The magnetic susceptibilities of [CuIILGdIII(o-van)(CH3COO)(MeOH)}2]·2H2O were analyzed by using a spin-only Hamiltonian H = −2J1(SCu1SGd1 + SCu2SGd2) − 2J2(SCu1SGd2 + SCu2SGd1) based on a cyclic tetranuclear structure and gave the best-fit parameters of g = 1.97, J1 = +3.8 cm−1, J2 = +0.7 cm−1, and zJ′ = −0.01 cm−1. The magnetization data at 2.0 K of [CuIILGdIII(o-van)(CH3COO)(MeOH)}2]·2H2O were well reproduced by using a Brillouin function with an S = 8 spin ground state due to the ferromagnetic interactions between CuII and GdIII ions and g = 1.97. The ac magnetic susceptibilities of [CuIILLnIII(o-van)(CH3COO)(MeOH)}2]·2H2O (LnIII = TbIII and DyIII) in the temperature range 1.8–10.0 K with a 3 G ac field oscillating in the range 1–1000 Hz showed a frequency dependence characteristic of SMMs.
合成并表征了三种四核
铜(II)-
镧系元素(III)配合物[CuIILLnIII(o-van)(CH3COO)(MeOH)}2]-2H2O(LnIII = GdIII、TbIII 和 DyIII)、其中 H3L 为 1-(2-羟基苯甲酰胺基)-2-(2-羟基-3-
甲氧基苯亚
氨基)
乙烷,o-van 为 3-甲氧基
水杨醛。这些化合物彼此同构,由环状四核 CuII2LnIII2 结构组成,其中 CuII 和 LnIII 离子交替排列,CuII 成分复合物为[CuIIL]-单元。[CuIIL]- 单元通过一侧的
苯酚氧原子和甲氧基氧原子以及另一侧的
氨基氧原子在两个相邻的 LnIII 离子之间起着 "桥接
配体-络合物 "的作用。从 2.0 到 300.0 K 的随温度变化的磁感应强度和 2.0 K 时 0 到 5 T 的随磁场变化的磁化率可以看出,CuII 与每个
镧系离子之间的磁性相互作用都是
铁磁性的。通过使用基于循环四核结构的纯自旋哈密顿 H = -2J1(SCu1SGd1 + SCu2SGd2) - 2J2(SCu1SGd2 + SCu2SGd1),分析了 [CuIILGdIII(o-van)(CH3COO)(MeOH)}2]-2H2O 的磁感应强度,并给出了最佳拟合参数 g = 1.97、J1 = +3.8 cm-1、J2 = +0.7 cm-1、zJ′ = -0.01 cm-1。使用布里渊函数,由于 CuII 和 GdIII 离子之间的
铁磁相互作用,S = 8 自旋基态和 g = 1.97,[CuIILGdIII(o-van)(CH3COO)(MeOH)}2]-2H2O 在 2.0 K 时的磁化数据得到了很好的再现。在 1.8-10.0 K 温度范围内,[CuIILLnIII(o-van)(CH3COO)(MeOH)}2]-2H2O(LnIII = TbIII 和 DyIII)在 1-1000 Hz 范围内振荡的 3 G 交流磁场中的交流磁感应强度显示出
SMM 的频率依赖性特征。