化学学报 ›› 2001, Vol. 59 ›› Issue (7): 1054-1058. 上一篇    下一篇

研究论文

草酸根桥联双核铜(Ⅱ)体系的磁耦合机理

胡海泉;刘成卜;刘永军;张冬菊;结思玮   

  1. 山东大学理论化学研究所.济南(250100);山东聊城师范学院物理系
  • 发布日期:2001-07-15

Magnetic coupling mechanism for an oxalato-bridged Cu(Ⅱ) dimer

Hu Haiquan;Liu Chengbu;Liu Yongjun;Zhang Dongju;Jie Siwei   

  1. Shandong Univ, Inst Theoret Chem.Jinan(250100)
  • Published:2001-07-15

应用密度泛函理论,采用对称性破损方法分析了草酸根桥联双核铜(Ⅱ)体系的磁耦合机理。在该双核体系中,两铜(Ⅱ)原子的自旋布居大小相等,符号相反,磁中心间的作用为反铁磁耦合。草酸根桥配体向磁中心的电子转移使得铜(Ⅱ)原子的自旋显著离域,这种离域有利于反铁磁耦合,草酸根桥配体中的碳原子上出现自旋极化。当铜(Ⅱ)原子的配位环境由平面四方形向四面体或四方锥变化时,反铁磁耦合的强度减弱。体系的沿前轨道主要由铜(Ⅱ)原子d轨道和配体原子p轨道构成,这种构成利于草酸根桥配体与磁中心之间的电子转移。

关键词: 桥键, 铜络合物, 双核配合物, 对称性破损, 密度函数, 草酸根络合物, 电子转移反应, 磁耦合

The magnetic coupling mechanism for an oxalato-brided Cu(Ⅱ) dimer has been analyzed using the density functional theory and the broken symmetry approach. The spin densities on two Cu(Ⅱ) atoms have the same values but with the opposite signs. The coupling between the two magnetic centers is antiferromagnetic, and the spin delocalization from the center toward its neighbors is significant. The strength of the coupling reduces while the envirnment around Cu(Ⅱ) atom charges from planar to tetrahedral geometry or square pyramid. The frontier orbitals are mainly composed of d-like orbitals of Cu(Ⅱ) atom and p- like orbitals of ligand. This constitution ofthe frontier orbitals favors the electron transfer from the oxalato ligand to the magnetic centers, leading to a strong antiferromagnetic coupling.

Key words: BRIDGE BOND, COPPER COMPLEX, DINUCLEAR COMPLEX, OXALATO COMPLEX, ELECTRON TRANSFER REACTION

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