4,4'-联吡啶、吡嗪和咪唑桥联铜、镍配合物的合成和磁性

合成了六个含氮杂环桥联配合物: Ni(salal)2(4,4'-bipy)]n、Ni(Et-dtp)2(4,4'-bipy)]n、Cu(acac)2(4,4'-bipy)]n、Cu(TTA)2(pyz)]n、Cu(TTa)(Im)]n和Cu(Im)2]n, 用元素分析、IR、MS、ESR和热重分析对它们的结构和性质作了表征。吡嗪配合物的晶体结构显示, 吡嗪配位于拉伸八面体的轴向位置, 桥联Cu(TTA)2形成一维无限链状结构。变温磁化率表明, 4,4'-联吡啶和吡嗪配合物的磁性遵从Curie-Weiss定律, 分子内没有明显的磁交换作用。咪唑配合物中存在着较强的反铁磁性交换作用, 磁交换常数分别为-75和-107cm^-^1。对4,4'-联吡啶、吡嗪和咪唑传递磁交换的性质作了讨论。

Synthesis and magnetic properties of Cu(II), Ni(II) complexes bridged by 4,4'-bipyridine, pyrazine and imidazole

Six-polynuclear complexes bridged by N-heterocycle, of formula Ni(salal)2(4,4'-bipy)]n, Ni(Et-dtp)2(4,4'-bipy)]n, Cu(acac)2(4,4'-bipy)]n、Cu(TTA)2(pyz)]n, Cu(TTa)(Im)]n and Cu(Im)2]n, were synthesized and characterized by elemental analysis, IR, MS, ESR and thermogravimetric analysis, Crystal structure analysis has proved that the complex Cu(TTA)2(pyz)]n has one-dimensional infinite linear structure. The local coordination geometry around Cu(II) is a distorted octahedron. The variable-temperature magnetic susceptibility determinations show that the magnetic properties of 4,4'-bipyridine and pyrazine bridging complexes obey the Curie-Weiss law. The imidazole complexes have strong antiferromagnetic interactions, the parameters 2J=-75cm^-^1 for Cu(TTA)(Im)]n and -107cm^-^1 for Cu(Im)2]n. Magnetic experimental data are discussed in the relation to the structures of 4,4'-bipyridine, pyrazine and imidazole. It is shown that 4,4'-bipyridine is not a good bridge for propagating a magnetic exchange interaction between n=metal ions.