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化学学报
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化学学报 ›› 1989, Vol. 47 ›› Issue (4): 333-339. 上一篇    下一篇

研究论文

金属Xchiff碱配合物的研究 II: 三价铁自旋变异晶态配合物的磁学和谱学表征

杨维达;谢传良   

  1. 华东师范大学化学系;武汉大学化学系
  • 发布日期:1989-04-15

Studies on metal complexes of schiff bases II: Magnetic and spectroscopic characterization of ferric spin-crossover schiff-base complexes in the solid state

YANG WEIDA;XIE CHUANLIANG   

  • Published:1989-04-15

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本文对五种组成为[Fe(3-EtO-SalAPA)2]ClO4.S的Fe(III)自旋变异晶态配合物进行了磁学和谱学表征, 所有溶剂合物的变温磁化率和EPR数据证示它们的自旋态转变性质均属渐变型, 在110-300K范围内的Mossbauer谱都只显示单一的四极分裂双峰. 实验结果还表明, 在所有晶态配合物中, Fe(III)自旋态的转变速率小于EPR谱学的时间标度(~10^1^0s^-^1), 而大于Mossbauer谱学的时间标度(~10^7s^-^1). 随着溶剂分子体积由C6H5F至o-C5H4Cl2的依次增大, 相应溶剂合物的μeff-T曲线的Tc值向低温方向位移.特别在单卤代苯系列中, 溶剂的分子体积与Tc值呈线性关系, 但氯苯溶剂合物是例外:后者的反常现象主要是由晶格内部的Tc≈185K时伴随发生了与自旋变异协同的一级相变所造成, 这个相变过程已为示差扫描量热测定和Mossbauer中心位移对温度的曲线呈现的不连续性所证实.

关键词: Ｘ射线衍射分析, 铁络合物, 示差扫描量热法, 变异性, 过渡金属络合物, 电子自旋共振, 席夫碱, 自旋, 磁化强度, 磁学

Continuous spin-crossover transformation is exhibited by the solvates of the composition [Fe(3-EtO-SalAPA)2]ClO4.S (where 3-EtO-SalAPA is the monoanionic Schiff base derived from 3-ethoxysalicylaldehyde and N-(3-aminopropyl)aziridine and S is C6H5F, C6H5Cl, C6H5Br, C6H5I or o-C6H4Cl2). Their gradual nature of spin-state interconversion is evidenced by the variable-temp. magnetic susceptibility and EPR data. Only a single quadrupole-split doublet is seen in the Moessbauer spectra for all solvates in the temperature range of 110-300 K. Thus, all complexes interconvert spin states slower than the EPR time scale (~10-10 s) but faster than the 57Fe Moessbauer time scale (~10-7 s). As the size of the solvate mol. S increases from C6H5F to o-C6H4Cl2 along the preceding sequence, the Tc value estimated from the meff vs. T curve of the corresponding solvate trends towards the lower temperature A linear relationship was observed between the mol. vols. of the monohalogenated benzene and the Tc values of the corresponding solvates, with the only exception being the chlorobenzene analog. This anomaly is attributed to a first-order phase transition occurred around 185 K, which coincides with the Tc value of this solvate.

Key words: X-RAY DIFFRACTION ANALYSIS, IRON COMPLEX, DIFFERENTIAL SCANNING CALORIMETRY, VARIABILITY, TRANSITION METAL COMPLEX, ELECTRON SPIN RESONANCE, SCHIFF BASE, SPIN, MAGNETIZATION, MAGNETISM

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