Two novel dinuclear nickel(II) complexes [Ni 2 (ntb) 2 (μ-tp)(H 2 O) 1.61 (CH 3 OH) 0.39 ](NO 3 ) 2 ·5.13CH 3 OH·2.25H 2 O (1) and [Ni 2 (ntb) 2 (μ-fum)(H 2 O)(CH 3 OH)](NO 3 ) 2 ·6CH 3 OH·H 2 O (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 11.333Å for 1 and 8.966Å 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 −0.25cm −1 and −0.36cm −1 , respectively.