Ligand Substituent Effects on the Spin-Crossover Behaviors of Dinuclear Iron(II) Compounds
Ligand Substituent Effects on the Spin-Crossover Behaviors of Dinuclear Iron(II) Compounds
复制标题
配体取代基对双核铁(II)化合物自旋交叉行为的影响
DOI：
10.1021/acs.inorgchem.8b02789
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发表时间：
2019
影响因子：
4.6
通讯作者：
Tao Jun
中科院分区：
文献类型：
--
作者：
Wang Chun Feng;Yao Zi Shuo;Yang Guo Yu;Tao Jun
合成了6个通式为[Fe 2（xL）5（NCS）4]·yMeOH（化合物1为x=o-Cl，y= 3;化合物2为x=m-Cl，y= 5;化合物3为x=p-Cl，y= 1;化合物4为x=o-Me，y = 2;化合物5为x=m-Me，y= 2;化合物6为x=p-Me，y= 3;化合物L为N-苯亚甲基-4-氨基-1，2，4-三唑）的类似物。两个Fe（II）离子通过三个L配体的三唑基团三重桥接，并且每个Fe（II）进一步被两个NCS-基团和一个morexL配体封端。这些化合物在其磁性中显示出依赖于取代基（-Cl或-Me）所处位置的规则模式，即，邻位取代化合物1和4发生了完全的一步自旋交叉（SCO），间位取代化合物2和5发生了不完全的一步自旋交叉，且转变温度较低，对位取代化合物3和6在所有温度范围内都处于高自旋态.结构分析表明，这些化合物的分子几何形状和分子间的相互作用，这应该占在磁性能的差异，显然取决于取代基的位置（空间效应），尽管它们是吸电子氯或给电子甲基，而理论计算证实，取代基的电子效应对磁性能没有影响。
Six analogue compounds with the general formula [Fe2(xL)5(NCS)4]·yMeOH (x=o-Cl,y= 3 for compound1;x=m-Cl,y= 5 for2;x=p-Cl,y= 1 for3;x=o-Me,y= 2 for4;x=m-Me,y= 2 for5;x=p-Me,y= 3 for6; L =N-phenylmethylene-4-amino-1,2,4-triazole) were synthesized. The two Fe(II) ions are triply bridged by the triazole groups of threexL ligands and each Fe(II) is further capped with two NCS–groups and one morexL ligand. These compounds show regular patterns in their magnetic properties that depend on the positions the substituent groups (−Cl or −Me) ride, i.e.,ortho-substituted compounds1and4undergo complete one-step spin crossover (SCO), whilemeta-substituted compounds2and5display incomplete one-step SCO with lower transition temperatures, andpara-substituted compounds3and6are in the high-spin states in all temperature ranges. Structural analyses reveal that the molecular geometry and intermolecular interactions of these compounds, which should account for the differences in magnetic properties, are obviously depend on the positions of substituent groups (steric effect), despite them being electron-withdrawing chlorine or electron-donating methyl, whereas theoretical calculations confirm that the electronic effects of substituent groups exert no effect on the magnetic properties.