A 4-amino-1,2,4-triazole (NH₂-trz) based linear trinuclear Fe(II) complex of [Fe₃(NH₂-trz)₆(SCN)₄(H₂O)₂](SCN)₂·H₂O (1) has been hydrothermally synthesized by the reaction of a NH₂-trz ligand with FeSO₄. A single crystal of complex 1 is able to extrude one lattice water and one coordinated water, leading to another single crystal of complex 1a with a formula [Fe₃(NH₂-trz)₆(SCN)₅(H₂O)](SCN) by heating. Complex 1a can be reversed to 1 upon the reabsorption of water. Single-crystal X-ray diffraction analysis reveals that these two complexes consist of a linear trinuclear core where a central Fe1 ion is coordinated to six nitrogen atoms from six bridged NH₂-trz ligands and one of the terminal Fe2 ions is coordinated to five nitrogen atoms and one oxygen atom. The terminal Fe3 ion in 1 coordinates to five nitrogen atoms and one oxygen atom; however, the terminal Fe3 ion in 1a coordinates to six nitrogen atoms. Magnetic susceptibility measurements demonstrate that they exhibited gradual spin crossover (SCO) for the central Fe(II) ion; however, different spin transition temperatures were displayed for complexes 1 and 1a (T_1/2 = 202 K for 1 and 160 K for 1a). These different spin transition temperatures arise from the different intermolecular hydrogen bonding interactions in the two complexes.

中文翻译：

---

水分子诱导具有不同自旋交叉行为的两个三核Fe（ii）配合物之间的可逆单晶至单晶转变†

[Fe ₃（NH ₂ -trz）₆（SCN）₄（H ₂ O）₂ ]（SCN ）的基于4-氨基-1,2,4-三唑（NH ₂ -trz）的线性三核Fe（II）络合物）₂ ·H ₂ O（1）已通过NH ₂ -trz配体与FeSO ₄的反应水热合成。配合物1的单晶能够挤出一种晶格水和一种配位水，从而生成另一种具有式[Fe ₃（NH ₂ -trz）₆（SCN）的配合物1a单晶。₅（H ₂ O）]（SCN）加热。复合物1a在重新吸收水后可以反转为1。单晶X射线衍射分析表明，这两个络合物由线性三核核组成，其中中心Fe1离子与六个桥连NH ₂ -trz配体的六个氮原子配位，并且一个末端Fe2离子与五个氮配位。原子和一个氧原子。1端的Fe3离子配位为5个氮原子和1个氧原子；然而， 1a中的末端Fe3离子配位为6个氮原子。磁化率测量表明，它们对中心Fe（ II）表现出逐渐的自旋交叉（SCO）） 离子; 然而，被显示络合物不同的自旋转变温度1和1A（Ť _1/2 = 202 K代表1和160 K中1A）。这些不同的自旋转变温度源自两种配合物中不同的分子间氢键相互作用。