Crystal structure of tri­aqua­(4-cyano­benzoato-κ(2) O,O′)(nicotinamide-κN (1))zinc 4-cyano­benzoate

The asymmetric unit of the title salt, [Zn(C(8)H(4)NO(2))(C(6)H(6)N(2)O)(H(2)O)(3)](C(8)H(4)NO(2)), contains one complex cation and one 4-cyano­benzoate (CNB) counter-anion. The Zn(II) atom in the cation is coordinated by one 4-cyano­benzoate ligand, one nicotinamide (NA) ligand and three water mol­ecules, the CNB anion thereby coordinating in a bidentate O,O′-mode through the carboxyl­ate group. The latter, together with one water O atom and the N atom of the NA ligand, form a distorted square-planar arrangement, while the considerably distorted octa­hedral coordination sphere of the Zn(II) atom is completed by the two O atoms of additional water mol­ecules in the axial positions. The dihedral angles between the planar carboxyl­ate groups and the adjacent benzene rings in the two anions are 10.25 (10) and 5.89 (14)°. Inter­molecular O—H⋯O hydrogen bonds link two of the coordinating water mol­ecules to two free CNB anions. In the crystal, further hydrogen-bonding inter­actions are present, namely N—H⋯O, O—H⋯O and C—H⋯O hydrogen bonds that link the mol­ecular components, enclosing R (2) (2)(12), R (3) (3)(8) and R (3) (3)(9) ring motifs and forming layers parallel to (001). π–π contacts between benzene rings [centroid-to-centroid distances = 3.791 (1) and 3.882 (1) Å] may further stabilize the crystal structure.