College of Chemistry, Tianjin Key Laboratory of Structure and Performance for Functional Molecules, Tianjin Normal University, Tianjin, 300387, PR China.
Dalton Trans. 2011 Aug 28;40(32):8132-9. doi: 10.1039/c1dt10394f. Epub 2011 Jul 5.
Three novel 3,5-diamino-1,2,4-triazole (Hdatrz)-based Co(II) coordination complexes, Co(Hdatrz)(0.5)(H(2)O)(2)(btec)(0.5) (1), {[Co(Hdatrz)(Hbtc)]·H(2)O}(n) (2) and Co(2)(datrz)(2)(nb)(2) (3) (H(4)btec = 1,2,4,5-benzenetetracarboxylic acid, H(3)btc = 1,3,5-benzenetricarboxylic acid and Hnb = 4-nitrobenzoic acid), were synthesized by incorporating different carboxylate-containing co-ligands and then were structurally and magnetically characterized. Complex 1 is a 3D pillared-layer framework with corrugated Co(II)-btec(4-) layers supported by neutral μ(2)-N1, N4-Hdatrz ligands. In contrast, the other two complexes are chiral (4, 4)- and racemic (4, 8(2))-topological layers with asymmetric μ(2)-N1, N4-Hdatrz-bridged helical chains extended by bis-monodentate Hbtc(2-) ligands for 2 and with a μ(3)-N1, N2, N4-datrz((-)) aggregated Shastry-Sutherland magnetic layer for 3. More interestingly, different magnetic phenomena with a field-induced metamagnetic transition from antiferromagnetic ordering to a ferromagnetic state for 1, spin-canted antiferromagnetism with a T(N) lower than 2.0 K for 2, as well as the coexistence of spin frustration and spin-flop transitions for 3 were observed, which, significantly, are governed by the local low-dimensional magnetic motifs mediated by the carboxylate and/or triazolate heterobridges in the anisotropic Co(II)-triazolate system.
三种新型的 3,5-二氨基-1,2,4-三唑（Hdatrz）配位的 Co(II)配合物，[Co(Hdatrz)(0.5)(H(2)O)(2)(btec)(0.5)]（n）（1），{[Co(Hdatrz)(Hbtc)]·H(2)O}（n）（2）和[Co(2)(datrz)(2)(nb)(2)]（n）（3）（H(4)btec = 1,2,4,5-苯四羧酸，H(3)btc = 1,3,5-苯三羧酸和 Hnb = 4-硝基苯甲酸），通过引入不同的含羧酸盐的共配体合成，并对其结构和磁性进行了表征。配合物 1 是一个 3D 支柱层骨架，由波纹状的 Co(II)-btec(4-)层支撑，中性 μ(2)-N1, N4-Hdatrz 配体位于层间。相比之下，另外两个配合物是手性（4,4）-和外消旋（4,8(2))-拓扑层，其中不对称的 μ(2)-N1, N4-Hdatrz 桥联螺旋链由双单齿 Hbtc(2-)配体延伸，对于 2 而言，以及一个 μ(3)-N1, N2, N4-datrz((-))聚集的 Shastry-Sutherland 磁层对于 3 而言。更有趣的是，观察到了不同的磁性现象，其中 1 表现出场诱导的反铁磁有序到铁磁态的顺磁转变，2 表现出低于 2.0 K 的自旋倾斜反铁磁性，以及 3 表现出自旋受挫和自旋跃变的共存，这显著地受到羧酸盐和/或三唑杂桥在各向异性 Co(II)-三唑体系中介导的局部低维磁矩的控制。
