Cu(II)/Cd(II) coordination polymers based on polycarboxylate and 2-(2-pyridyl)benzimidazole

catena-Poly[[triaqua-nickel(II)]-μ-5-carb-oxy-benzene-1,3-dicarboxyl-ato-κO:O]

In the title compound, [Ni(C₉H₄O₆)(H₂O)₃]_n, the Ni^II ion has a distorted NiO₅ square-pyramidal geometry, the maximum deviation from the least-squares plane formed by the basal atoms being 0.9351 (13) Å. The basal plane is formed by two O atoms from carboxyl­ate residues of the 5-carb­oxy­benzene-1,3-dicarboxyl­ate ligand and by two O atoms from water mol­ecules. The O atom of the third water mol­ecule is axially positioned, 1.7890 (19) Å perpendicular to the basal plane. The 5-carb­oxy­benzene-1,3-dicarboxyl­ate ligand bridges the metal atoms, forming a polymeric chain along the b axis. O—H⋯O hydrogen bonds between the water mol­ecules and carboxyl­ate groups stabilize the crystal structure.