Hagiwara Hiroaki, Tanaka Tomoko, Hora Shiori
Department of Chemistry, Faculty of Education, Gifu University, Yanagido 1-1, Gifu 501-1193, Japan.
Graduate School of Education, Gifu University, Yanagido 1-1, Gifu 501-1193, Japan.
Dalton Trans. 2016 Nov 1;45(43):17132-17140. doi: 10.1039/c6dt02766k.
A mononuclear iron(ii) complex, Fe(L1) (1), and a related dinuclear one, Fe(L2)·5HO·MeCN (2), were prepared, where L1 is a tridentate N coordinating Schiff-base ligand, 1-methyl-1,2,3-triazol-4-yl-methylideneamino-2-ethylpyridine, and L2 is a dimeric form ligand of L1, 1,1'-(1,2-ethanediyl)bis-1,2,3-triazol-4-yl-methylideneamino-2-ethylpyridine, and their magnetostructural relationships were investigated. Mononuclear 1 shows a gradual one-step spin crossover (SCO) from the low-spin (LS) state (S = 0) at room temperature (RT) to the mostly high-spin (HS) state (S = 2) at 470 K spanning a temperature range of more than 170 K, while dinuclear 2 shows an anomalous two-step SCO with a gradual transition in a first step from the LS-LS state at RT to around 432 K and then an abrupt spin transition centred at 432 K with 11 K wide hysteresis in a second step (T = 437 K and T = 426 K) reaching the mostly HS-HS state. Single crystal X-ray structure analyses revealed that the iron(ii) centre of mononuclear 1 has an N6 octahedral coordination environment with two tridentate L1 ligands, while the complex-cation of 2 has a dinuclear double helicate architecture as though a dimeric form of two complex-cations of 1 replaced their methyl group with a bridging ethylene chain. Both complexes have a cationic two-dimensional (2D) structure in which the 2D layer of mononuclear 1 is constructed of intermolecular CHN hydrogen bonds between adjacent complex-cations, while that of dinuclear 2 is constructed of both intermolecular π-π and CH/π interactions between neighboring helicates.
制备了单核铁（II）配合物Fe(L1)（1）和相关的双核配合物Fe(L2)·5H₂O·MeCN（2），其中L1是一种三齿N配位席夫碱配体，1-甲基-1,2,3-三唑-4-基亚甲基氨基-2-乙基吡啶，L2是L1的二聚体形式配体，1,1'-（1,2-乙二基）双-1,2,3-三唑-4-基亚甲基氨基-2-乙基吡啶，并研究了它们的磁结构关系。单核配合物1在室温（RT）下从低自旋（LS）态（S = 0）到470 K时主要为高自旋（HS）态（S = 2）呈现出逐渐的一步自旋交叉（SCO），跨越温度范围超过170 K，而双核配合物2呈现出异常的两步SCO，第一步从RT时的LS-LS态逐渐转变至约432 K，然后在第二步（T = 437 K和T = 426 K）以432 K为中心发生突然的自旋转变，具有11 K宽的滞后，达到主要为HS-HS态。单晶X射线结构分析表明，单核配合物1的铁（II）中心具有由两个三齿L1配体构成的N₆八面体配位环境，而配合物2的阳离子具有双核双螺旋结构，就好像两个单核配合物1的阳离子二聚体形式通过桥连的乙烯链取代了它们的甲基。两种配合物都具有阳离子二维（2D）结构，其中单核配合物1的2D层由相邻配合物阳离子之间的分子间CHN氢键构成，而双核配合物2的2D层由相邻螺旋体之间的分子间π-π和CH/π相互作用构成。
