Solid-State Spin Equilibrium of Ni(cyclam)2 Complex: Magnetostructural Correlations in Two Polymorphs.,Inorganic Chemistry

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Solid-State Spin Equilibrium of Ni(cyclam)2 Complex: Magnetostructural Correlations in Two Polymorphs.
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2020-03-31 , DOI: 10.1021/acs.inorgchem.9b03735
Yoji Horii ₁ , Yuki Kanegae ₁ , Kiyonori Takahashi ₂ , Akira Fuyuhiro ₃ , Mariko Noguchi ₁ , Hal Suzuki ₄ , Motohiro Nakano ₁

Affiliation

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 polymorph trans-[Ni(cyclam)I2] (1a), whereas the zigzag-chain polymorph catena-[Ni(cyclam)(μ-I)]I (1b) did not show an obvious spin transition. The entropy difference between high- and low-spin states of 1a estimated 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 in 1a. 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 and x,y-shortening of the coordination octahedron.

中文翻译：

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。

合成了Ni（cyclam）I2的两个晶体多晶型物（cyclam = 1,4,8,11-四氮杂环十四烷），并研究了它们的磁性。与温度有关的X射线结构分析和磁性测量表明，分子晶体多晶型物反式[[Ni（cyclam）I2]（1a）具有逐渐的自旋跃迁，而之字形链多晶型物catena- [Ni（cyclam）（μ-I））] I（1b）没有显示出明显的自旋转变。通过假设自旋平衡模型估计的1a高和低自旋状态之间的熵差比典型的基于铁（II）的自旋交叉（SCO）络合物的熵差小得多，这表明正常模式下的软化作用较小在1a中表现出色。在该系统中，清楚地证明了八面体镍（II）配合物中自旋平衡的相互作用模式是高度各向异性的，即

更新日期：2020-04-24

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