Solid-State Spin Equilibrium of Ni(cyclam)2 Complex: Magnetostructural Correlations in Two Polymorphs
Solid-State Spin Equilibrium of Ni(cyclam)2 Complex: Magnetostructural Correlations in Two Polymorphs
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Ni(cyclam)2 配合物的固态自旋平衡：两种多晶型物的磁结构相关性
DOI：
10.1021/acs.inorgchem.9b03735
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发表时间：
2020
影响因子：
4.6
通讯作者：
Motohiro Nakano
中科院分区：
文献类型：
--
作者：
Yoji Horii;Yuki Kanegae;Kiyonori Takahashi;Akira Fuyuhiro;Mariko Noguchi;Hal Suzuki;Motohiro Nakano
合成了Ni(cyclam)I2（cyclam = 1,4,8,11-四氮杂环十四烷）的两种晶型，并对其磁性进行了研究。温度相关的x射线结构分析和磁测量表明，分子晶体多晶trans-[Ni(cyclam)I2] （1a）的自旋转变是渐进的，而锯齿链多晶catena-[Ni(cyclam)(μ-I)]I （1b）的自旋转变不明显。假设自旋平衡模型估计的a的高自旋态和低自旋态的熵差比典型的铁基自旋交叉（SCO）配合物的熵差小得多，表明a的正态软化不那么显著。在这个体系中，清楚地证明了八面体镍（II）配合物中负责自旋平衡的相互作用模式是高度各向异性的，即配位八面体的z-伸长和x，y-缩短。
Two crystal polymorphs of Ni(cyclam)I2(cyclam = 1,4,8,11-tetraazacyclotetradecane) were synthesized, and their magnetic properties were investigated. Temperature-dependent X-ray structural analysis and magnetic measurements revealed gradual spin transition in molecular-crystal polymorphtrans-[Ni(cyclam)I2] (1a), whereas the zigzag-chain polymorphcatena-[Ni(cyclam)(μ-I)]I (1b) did not show an obvious spin transition. The entropy difference between high- and low-spin states of1aestimated by assuming the spin-equilibrium model is much smaller than those in typical iron(II)-based spin-crossover (SCO) complexes, suggesting that the normal mode softening is less remarkable in1a. In this system, it is clearly evidenced that the interaction mode responsible to the spin equilibrium in octahedral nickel(II) complexes is highly anistropic, i.e.,z-elongation andx,y-shortening of the coordination octahedron.