A precise regulation of the temperature of spin crossover (SCO) is an essential task to envisage practical applications of switchable materials. Here, we present three isostructural complexes with the formula [Fe(L_Cl)(NCE)₂], where L_Cl is the tetradentate ligand N,N′-bis[(4-chloro-2-pyridyl)methyl]ethane-1,2-diamine and E = S (1-S), Se (1-Se), and BH₃ (1-BH₃). Single-crystal X-ray diffraction, magnetic measurements, Mössbauer spectroscopy and DSC measurements have been carried out to study their SCO properties. 1-S remains in a high spin state over all temperatures due to the weak ligand field strength imposed by NCS⁻ ligands. The replacement of NCS⁻ by NCSe⁻ allows the occurrence of SCO around 177 K. Using NCBH₃⁻ instead allows a further increase of the conversion temperature (T_1/2) by ca. 30 K. A literature survey of complexes containing NCE⁻ ligands was carried out to examine their influence on the SCO properties. A 50–90 K difference in T_1/2 was found between NCS⁻ and NCSe⁻ derivatives and a 30–50 K difference was found between NCSe⁻ and NCBH₃⁻ derivatives.

中文翻译：

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NCE的影响^-（E = S，SE，BH ₃）上自旋交叉的温度配体在一个家庭中的铁（的II）单核配合†

精确调节自旋交越点（SCO）的温度是设想可转换材料的实际应用的一项基本任务。在这里，我们提出了三种具有[Fe（L _Cl）（NCE）₂ ]的同构配合物，其中L _Cl是四齿配体N，N'-双[（4-氯-2-吡啶基）甲基]乙烷-1 ，2-二胺和E ＝ S（1-S），Se（1-Se）和BH ₃（1-BH ₃）。已经进行了单晶X射线衍射，磁测量，穆斯堡尔光谱和DSC测量以研究其SCO特性。1一由于NCS施加的弱配位场强度保持在过所有的温度高自旋状态^-配体。NCS的更换^-通过NCSE ^-允许SCO的周围177 K.使用NCBH发生₃ ^-代替允许转化温度的（进一步增加Ť _1/2）通过约 30含有NCE配合物K.文献调查^-配体进行了研究它们对SCO性能的影响。在甲50-90ķ差Ť _1/2被NCS之间发现^-和NCSE ^-衍生物和30-50ķ差被发现NCSE之间^-和NCBH ₃ ^-衍生物。