Brachňaková Barbora, Matejová Simona, Moncol Ján, Herchel Radovan, Pavlik Ján, Moreno-Pineda Eufemio, Ruben Mario, Šalitroš Ivan
Department of Inorganic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Bratislava SK-81237, Slovakia.
Department of Inorganic Chemistry, Faculty of Science, Palacký University, 17. listopadu 12, 771 46 Olomouc, Czech Republic.
Dalton Trans. 2020 Jan 28;49(4):1249-1264. doi: 10.1039/c9dt04592a. Epub 2020 Jan 6.
A tridentate ligand L (2,6-bis(1-(3,5-di-tert-butylbenzyl)-1H-benzimidazol-2-yl)pyridine) was synthesized and used for the preparation of three pentacoordinated Co(ii) complexes of formula [Co(L)X] (where X = NCS for 1, X = Cl for 2 and X = Br for 3) and one ionic compound 4 ([Co(L)]Br·2CHOH·HO) containing a hexacoordinated Co(ii) centre. Static magnetic data were analysed with respect to the spin (1-3) or the Griffith-Figgis (4) Hamiltonian. Ab initio calculations enable us to identify the positive axial magnetic anisotropy parameter D accompanied by a significant degree of rhombicity in the reported complexes. Also, magneto-structural correlation was outlined for this class of compounds. Moreover, all four compounds exhibit slow relaxation of magnetisation at an applied static magnetic field with either both low- and high-frequency relaxation channels (3) or a single high-frequency relaxation process (1, 2 and 4). The interplay between the stereochemistry of coordination polyhedra, magnetic anisotropy and the relaxation processes was investigated and discussed in detail.
合成了一种三齿配体L（2,6-双（1-（3,5-二叔丁基苄基）-1H-苯并咪唑-2-基）吡啶），并用于制备三种通式为[Co(L)X]的五配位Co(ii)配合物（其中X = NCS时为1，X = Cl时为2，X = Br时为3）以及一种含有六配位Co(ii)中心的离子化合物4（[Co(L)]Br·2CHOH·HO）。针对自旋（1 - 至3）或格里菲斯 - 菲吉斯（4）哈密顿量对静态磁数据进行了分析。从头算计算使我们能够确定所报道配合物中伴随显著菱形度的正轴向磁各向异性参数D。此外，还概述了此类化合物的磁结构相关性。而且，所有四种化合物在施加静态磁场时均表现出磁化强度的缓慢弛豫，其中3具有低频和高频弛豫通道，而1、2和4具有单一高频弛豫过程。详细研究并讨论了配位多面体的立体化学、磁各向异性与弛豫过程之间的相互作用。
