Synthesis, structures and magnetic properties of nicotinato-copper(II) complexes with polybenzimidazole and polyamine ligands

Four novel nicotinato-copper(II) complexes containing polybenzimidazole and polyamine ligands were synthesized with formula [Cu(2)(bbma)(2)(nic)(2)](ClO(4))(2)center dot CH(3)OH center dot 0.5H(2)O (1), [Cu(2)(dien)(2)(nic)(2)](ClO(4))(2)center dot 2CH(3)OH (2), [Cu(ntb)(nic)]ClO(4)center dot H(2)O (3) and [Cu(tren)(nic)]BPh(4)center dot CH(3)OH center dot H(2)O (4), in which bbma is bis(benzimidazol-2-yl-methyl)amine, dien is diethylenetriamine, ntb is tris(2-benzimidazolylmethyl)amine, tren is tris(2-aminoethyl) amine and nic is nicotinate anion. All of the complexes were characterized by elemental analysis, IR and X-ray diffraction analysis. Complexes 1 and 2 contain centrosymmetric dinuclear entity with the two Cu(II) atoms bridged by two nicotinate anions in an anti-parallel mode. The Cu center dot center dot center dot Cu separation is 7.109 angstrom for 1 and 6.979 angstrom for 2. Complexes 3 and 4 are mononuclear with nicotinate coordinated to Cu(II) ion by the carboxylate O atom in 3 and the pyridine N atom in 4. All of the complexes exhibit abundant hydrogen bonds to form 1D chain for 1, 3, 4 and 2D network for 2. Magnetic susceptibility measurements over the 2-300 K range reveal very weak ferromagnetic interaction between the two Cu(II) ions in 1 and antiferromagnetic interaction in 2 mediated by nicotinate ligand, with J value to be 0.15 and -0.19 cm (1), respectively. (C) 2010 Elsevier B. V. All rights reserved.