取代基团对吡唑硼-亚铁体系自旋交叉配合物性能的影响

Effects of Substituents on Properties of Spin Crossover Complexes in Pyrazole Boron-Ferrous System

通过不同取代基对吡唑环配体进行修饰,制备了6种基于吡唑硼-亚铁的自旋交叉配合物,研究了取代基对自旋转变性能的影响。实验发现,吡唑硼-亚铁配合物均具有渐变型的自旋转变特性。吸电子取代基可以降低吡唑环的电子云密度,有利于低自旋态稳定,使得自旋转变温度升高;供电子取代基则增加了吡唑环的电子云密度,有利于高自旋态稳定,使得自旋转变温度降低;此外,具有较大空间位阻的取代基会抑制Fe-N键的增长,有利于低自旋态的稳定,使得自旋转变温度升高。本研究表明自旋交叉配合物的自旋转变温度可以通过配体修饰实现有效调控。

Six spin crossover complexes(SCOs)based on pyrazole boron ferrous complexes were prepared by the modification on pyrazole ligand with different substituents,and the effects of substituents on spin transition properties were investigated.It is found that pyrazole boron ferrous complexes possess spin transition properties in a gradual process.The electron-withdrawing groups reduce the density of electron cloud in pyrazole ring,which is beneficial to the stability of low spin states,resulting in a higher spin transition temperature.While the electron-donating groups enhance the density of electron cloud in pyrazole ring,which is beneficial to the stability of high spin states,resulting in a lower spin transition temperature.In addition,the substituent with large steric hindrance restrains the increase of Fe-N bond,which is beneficial to the stability of low spin states,resulting in a higher spin transition temperature.The study indicates that spin transition temperature of SCOs can be effectively regulated by ligand modification.