Synthesis, crystal structures and magnetic studies of terephthalato- and fumarato-bridged dinickel(II) complexes with tripodal poly-benzimidazole ligand

Abstract

Two novel dinuclear nickel(II) complexes [Ni 2(ntb) 2(μ-tp)(H 2O) 1.61(CH 3OH) 0.39](NO 3) 2·5.13CH 3OH·2.25H 2O (1) and [Ni 2(ntb) 2(μ-fum)(H 2O)(CH 3OH)](NO 3) 2·6CH 3OH·H 2O (2) (tp = terephthalate dianion, fum = fumarate dianion, ntb = tris(2-benzimidazolylmethyl)amine) containing tetradentate poly-benzimidazole ligand were synthesized and structurally characterized by IR spectra, UV–Vis, elemental analysis and X-ray crystallography. The Ni(II) ions in 1 and 2 have distorted octahedral geometry with four nitrogen atoms of ntb, one oxygen atom of water and one oxygen atom supplied by the carboxylate group of the bridged dicarboxylato ligand. Complexes 1 and 2 consist of terephthalato- and fumarato-bridged dinickel(II) centers in bis(monodentate) bonding fashion. The Ni ⋯ Ni distances are 11.333 Å for 1 and 8.966 Å for 2. The magnetic susceptibility measurements at variable temperature show that two complexes exhibit weak antiferromagnetic interactions between nickel(II) ions with J values of −0.25 cm −1 and −0.36 cm −1, respectively.