Four new coordination polymers constructed using 2,2′-oxybis(benzoic acid) and auxiliary N-donor ligands: Syntheses, structures, magnetic behavior and DFT studies

Four new coordination polymers [Cu(oba)(phen)] (1), [Co(oba)(phen)] (2), [Ni-2(oba)(2)(bpe)] (3) and [Ni(oba)(bpe)(1.5)]center dot 2.5H(2)O (4) [H(2)oba = 2,2'-oxybis(benzoic acid), phen = 1,10-Phenanthroline, bpe = 1,2-bis(4-pyridyl)ethylene] were synthesized by hydrothermal reactions and characterized by single-crystal X-ray diffraction, thermogravimetric analyses, IR spectroscopy and elemental analysis. Compound 1 shows a discrete binuclear structure. Compound 2 is a right-handed 1D helical chain, though pi-pi stacking interactions to form a 2D wavelike network. Compound 3 displays a 2D wavy layer with the paddle-wheel SBUs. Compound 4 features a 2-fold interpenetrating 3D structure with 2D brick-wall networks. The magnetic properties of compounds 1, 2 and 4 have also been investigated. According to the crystal structures, the full geometry optimizations of compounds 1-4 were carried out by using hybrid DFT methods at B3LYP/6-31G(d) level. Meantime, the DFT-BS approach was applied to study the magnetic coupling behavior for compounds 1, 2 and 4, the result reveals that the calculated exchange coupling constants J were in good agreement with the experimental data. (C) 2014 Elsevier Ltd. All rights reserved.