Crystal structure of catena-poly[[[tri-aqua-(4-cyano-benzoato-κO)nickel(II)]-μ-4,4'-bi-pyridine-κ(2) N:N'] 4-cyano-benzoate].

In the title polymeric complex salt, {[Ni(C8H4NO2)(C10H8N2)(H2O)3](C8H4NO2)} n , the Ni(II) cation is coordinated by a 4-cyano-benzoate anion, two 4,4'-bi-pyridine ligands and three water mol-ecules in a distorted N2O4 octa-hedral geometry. The 4,4'-bi-pyridine ligands bridge the Ni(II) cations to form polymeric chains of the title complex cations, propagating along the c-axis direction. The dihedral angle between the pyridine rings of the 4,4'-bi-pyridine ligand is 24.9 (6)°. In the crystal, the uncoordinating 4-cyano-benzoate anions link with the complex cations via O-H⋯O hydrogen bonds into a three-dimensional supra-molecular architecture. Weak C-H⋯O, C-H⋯N inter-actions and π-π stacking [centroid-to-centroid distances = 3.566 (4) and 3.885 (4) Å] are also observed in the crystal.