Brachňaková Barbora, Adamko KoŽíšková Júlia, KoŽíšek Jozef, Melníková Eva, Gál Miroslav, Herchel Radovan, Dubaj Tibor, Šalitroš Ivan
Department of Inorganic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Bratislava SK-81237, Slovakia.
Dalton Trans. 2020 Dec 22;49(48):17786-17795. doi: 10.1039/d0dt03497e.
Two tridentate ligands (L1 = 2,6-bis(1-(3,5-di-tert-butylbenzyl)-1H-benzimidazol-2-yl)pyridine and L2 = 2,6-bis(1-(4-tert-butylbenzyl)-1H-benzimidazol-2-yl)pyridine) and one didentate ligand (L3 = 1-(4-tert-butylbenzyl)-2-pyridine-2-yl-1H-benzimidazol) were used for the synthesis of eight mononuclear Fe(ii) compounds 1-8 containing miscellaneous counterions. Single-crystal X-ray diffraction analysis confirmed the expected molecular structures of all the reported coordination compounds and revealed the octahedral geometry of metal centres in the complex dications of 1-8. Compounds 1-6 prepared from tridentate ligands were low-spin and, therefore, diamagnetic up to 400 K. On the other hand, compounds 7 and 8, in which the Fe(ii) centre was coordinated with didentate ligand L3, exhibited temperature and light triggered spin-crossover behaviour. The theoretical calculations supported the experimental magnetic investigation and helped to explain the electronic structures of the reported complexes with respect to the occurrence of thermal and light induced spin state switching. In addition, the solution redox properties of compounds 1-8 were investigated by cyclic voltammetry.
使用两种三齿配体（L1 = 2,6 - 双(1 - (3,5 - 二叔丁基苄基)-1H - 苯并咪唑 - 2 - 基)吡啶和L2 = 2,6 - 双(1 - (4 - 叔丁基苄基)-1H - 苯并咪唑 - 2 - 基)吡啶）以及一种双齿配体（L3 = 1 - (4 - 叔丁基苄基)-2 - 吡啶 - 2 - 基 - 1H - 苯并咪唑）合成了八种含有不同抗衡离子的单核铁(ii)化合物1 - 8。单晶X射线衍射分析证实了所有报道的配位化合物的预期分子结构，并揭示了1 - 8的配合物二价阳离子中金属中心的八面体几何构型。由三齿配体制备的化合物1 - 6是低自旋的，因此在400 K以下是抗磁性的。另一方面，其中铁(ii)中心与双齿配体L3配位的化合物7和8表现出温度和光触发的自旋交叉行为。理论计算支持了实验磁性研究，并有助于解释所报道配合物的电子结构与热诱导和光诱导自旋态转换的发生情况。此外，通过循环伏安法研究了化合物1 - 8的溶液氧化还原性质。
