Synthesis, characterization and magnetism of binuclear cobalt(Ⅱ) complexes bridged by tetracarboxylato groups

• 来源期刊: 中国化学（英文版）
• 年，卷（期）: 2000,（3）
• 页码范围: 351-356
• 页数: 6页
• 语种: 英文

摘要

Three new binuclear cobalt(Ⅱ) complexes with extended tetracarboxylato-bridge have been synthesized and character-ized, namely [Co2(PMTA) (bpy)4] (1), [Co2(PMTA)-(phen)4] (2) and [Co2(PMTA)(NO2plen)4] (3), where PMTA represents the tetraanion of pyromellitic acid, and bpy, phen, NO2-phen denote 2,2＇-bipyridine, 1, 10-phenanthroline; 5-nirto-1,10-phenanthroline, respectively. Based on elemental analyses, molar conductivity measurements, IR and electronic spectra studies, it is proposed that these complexes have PMTA-bridged structures and consist of two cobalt(Ⅱ)ions, each in a distorted octabedral environment. These complexes were further characterized by variable temperature magnetic susceptibility measurements (4－300 K) and the observed data were successfully simulated by the equatiou based on the spin Hamiltonian operator, Й= - 2JS· S2, giving the exchange integral J = - 1.02 cm-1 for 1, J = - 1.21 cm-1 for 2 and J = - 1.18 cm-1 for 3, respectively. These results revealed the operation of antiferromagnetic spin-exchange interaction between the two Co(Ⅱ) ions within each molecule.