Low-spin and spin-crossover iron(II) complexes with pyridyl-benzimidazole ligands: synthesis, and structural, magnetic and solution study.
Low-spin and spin-crossover iron(II) complexes with pyridyl-benzimidazole ligands: synthesis, and structural, magnetic and solution study.
复制标题
具有吡啶基苯并咪唑配体的低自旋和自旋交叉铁 (II) 配合物：合成以及结构、磁性和溶液研究。
作者：
Barbora Brachňaková;Júlia Adamko KoŽíšková;J. Kožíšek;E. Melníková;M. Gál;R. Herchel;T. Dubaj;Ivan Šalitroš
两个三齿配体（L1 = 2，6-双（1-（3，5-二叔丁基苄基）-1H-苯并咪唑-2-基）吡啶且L2 = 2，6-双（1-（4-叔丁基苄基）-1H-苯并咪唑-2-基）吡啶）和一个二齿配体（L3 = 1-（4-叔丁基苄基）-2-吡啶-2-基-1H-苯并咪唑）用于合成八个单核Fe（ii）化合物1- 8含有杂反离子。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，并揭示了八面体几何的金属中心在复杂的dications 1-8。从三齿配体制备的化合物1-6是低自旋的，因此，在高达400 K下是抗磁性的。另一方面，化合物7和8，其中的Fe（ii）中心与二齿配体L3协调，表现出温度和光引发的自旋交叉行为。理论计算支持了实验磁性调查，并有助于解释的电子结构的报告复合物相对于发生的热和光诱导的自旋态转换。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。
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.