catena-Poly[[[diaqua­diformatonickel(II)]-μ-1,4-bis­(1H-benzimidazol-1-yl)benzene] dihydrate]

In the title one-dimensional coordination polymer, {[Ni(CHO2)2(C20H14N4)(H2O)2]·2H2O}n, the NiII atom lies on a crystallographic inversion centre. It is coordinated by two formate O atoms, two water O atoms and two N atoms from two 1,4-bis­(1H-benzimidazol-1-yl)benzene (bzb) ligands, resulting in a distorted trans-NiN2O4 octa­hedral coordination geometry. The bzb mol­ecule acts as a bridging ligand to connect the metal atoms into a chain propagating in [1\overline{1}\overline{1}]. The dihedral angle between the benzimidazole ring and the central benzene ring in the ligand is 38.16 (9)°. In the crystal, O—H⋯O hydrogen bonds crosslink the chains into (010) sheets.