以均苯四甲酸根为桥联配体的双核钴(II) 配合物的合成与磁性

作者合成和表征了3个通式为[Co2(PMTA)L4]的新双核钴(II)配合物,其中,PMTA代表均苯四甲酸根四价阴离子,L分别为邻苯二胺(obda)、2-二甲氨基乙胺(Me2en)和3-二甲氨基丙胺(Me2pn).根据元素分析、摩尔电导测定、红外和电子光谱等手段,已推定这些配合物具有均苯四甲酸根桥联的双核钴(II)结构,其中,两个钴(II)离子均处于畸变的八面体配位环境.作者还测定并解析了配合物[Co2(PMTA)(Me2pn)4]的变温(4～300K)磁化率,求得交换积分J=-0.28cm-1.根据实验结果作者认为,在双核钴(II)配合物中的钴(II)离子间存在极弱的反铁磁自旋超交换作用.

SYNTHESIS AND MAGNETICPROPERTIES OF BINUCLEAR COBALT( II ) COMPLEXES WITH TETRACARBOXYLATO GROUPS AS BRIDGINGLIGAND

Three new (μ-tetracarboxylato binuclear cobalt (II) complexes described by the overall formula [ Co2 (PMTA)(L)4], where PMTA represents the tetraanion of pyromellitic acid;and L denotes o-benzenediarnine (obda), 2-dimethylaminoethylarnine (Me2en) or 3- dimethylaminopropylamine (Me2pn), respectively, have been synthesized and characterized by elemental analyses, molar conductivity measurements, IR and electronic spectra. It is proposed that these conplexes have PMTA-bridged structures and consist of two cobalt(II) ions, each in a distorted octahedral environment. The [ Co2 (PMTA) ( Me2pn)4 ] complex was further characterized by variable temperature magnetic susceptibility measurements (4～ 300 K) and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, H = 2JS1 @S2, giving the exchange integral J = - 0.28 cm- 1. The result revealed the operation of antiferromgnetic spin-exchange interaction between the two Co(II) ions within the molecule.