catena-Poly[[[diaqua-diformato-cobalt(II)]-μ-1,4-bis-(1H-benzimidazol-1-yl)benzene] dihydrate].

In the title coordination polymer, {[Co(CHO(2))(2)(C(20)H(14)N(4))(H(2)O)(2)]·2H(2)O}(n), the Co(II) atom (site symmetry [Formula: see text]) 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 ligands (L), resulting in a distorted trans-CoN(2)O(4) octa-hedral coordin-ation environment. The complete L ligand is generated by crystallographic inversion symmetry and serves to bridge the cobalt ions into a chain propagating in [1[Formula: see text][Formula: see text]]. The dihedral angle between the central benzene ring and the imidazole ring system is 38.48 (12)°. O-H⋯O hydrogen bonds involving both the coordinated and uncoordinated water mol-ecules occur and help to link the chains together.