Two Carboxylato-bridged Binuclear Cobalt(II) Complexes Pillared Coligands: Synthesis, Structures and Magnetic Properties

By adopting mixed-ligand strategy, two Co(II) coordination polymers, [Co(phda)(itmb)(H2O)(2)]n(1) and [Co(phda)(Hpytz)k (2) (H(2)phda = 1,2-phenylenediacetate, itmb = 1-(imidazo-1-ly)-4-(1,2,4-triazol-1-yl methyl) benzene and Hpytz = 3,5-di(4-pyridy1)-1,2,4-triazolate), were hydrothermally synthesized and then characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. The single-crystal X-ray diffraction reveals that two complexes feature carboxylato-bridged binuclear subunits extended further by the nitrogen-rich coligands to form different structures. Complex 1 containing phda-bridged binuclear cobalt is developed by itmb coligand to 1D double-stranded chain, whereas complex 2 exhibits 2D open bilayers, which result from the ribbon-like carboxylate chains pillared Hpytz coligands. In addition, the magnetic susceptibilities of both compounds were measured over the temperature range of 3-300 K, and the data were analyzed well using MagSaki software. The best fitting parameters were kappa = 0.98, lambda = -100 cm(-1) Delta = 588 cm(-1) and J = 0.6 cm(-1) for complex 1 and kappa = 0.86, lambda = -110 cm(-1), Delta = 756.8 cm(-1) and J = -1.25 cm(-1) for complex 2. The results indicate the existence of weaker ferromagnetic interaction for complex 1 and antiferromagnetic interaction for complex 2 between the metal centers in the dinuclear metal units.