Three Co(II) coordination polymers constructed using 2,2 '-oxybis(benzoic acid) and auxiliary N-donor ligands: Syntheses, structures, magnetic behavior and density functional theory studies

摘要

Three new coordination polymers [Co(2,2-oba)(2,2'-bipy)(H2O)(2)] (1), [Co(2,2'-oba)(4,4'-bimbP)(1.5)] center dot 1.5H(2)O (2), and [Co(2,2'-oba)(4,4 bimbP)(0.5)(H2O)]center dot H2O (3) [2,2 -H-2 oba = 2,2'-oxybis(benzoic acid), 2,2'-bipy = 2,2'bipyridine, 4,4'-bimbp = 4,4'-bis(imidazoly)biphenyl] 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, due to the intermolecular C-H center dot center dot center dot O hydrogen bonds, the adjacent binuclear units are connected to produce a 3D supramolecular structure. Compound 2 shows an interlocking 3D structure, that is made of the infinite parallel polycatenation of the 1D chain (1D + 1D - 3D). Compound 3 displays an infinite polymeric chain, further these chains are joined by O-H center dot center dot center dot O hydrogen bonding to produce a 2D supramolecular architecture. The magnetic properties of compounds 1-3 have also been investigated, the exchange interctions were -13.91 cm(-1), -0.69 cm(-1) and -2.29 cm(-1), respectively. According to the crystal structures, compounds 1-3 were carried out by using hybrid DFT methods at B3LYP/6-31G (d) level, the DFT-BS approach was applied to study the magnetic coupling behavior for compounds 1-3, the result reveals that the calculated exchange coupling constants J were in good agreement with the experimental data.