Crystal structure of tri-aqua-(4-cyano-benzoato-κ(2) O,O')(nicotinamide-κN (1))zinc 4-cyano-benzoate.

The asymmetric unit of the title salt, [Zn(C8H4NO2)(C6H6N2O)(H2O)3](C8H4NO2), contains one complex cation and one 4-cyano-benzoate (CNB) counter-anion. The Zn(II) atom in the cation is coordinated by one 4-cyano-benzoate ligand, one nicotinamide (NA) ligand and three water mol-ecules, the CNB anion thereby coordinating in a bidentate O,O'-mode through the carboxyl-ate 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 octa-hedral coordination sphere of the Zn(II) atom is completed by the two O atoms of additional water mol-ecules in the axial positions. The dihedral angles between the planar carboxyl-ate groups and the adjacent benzene rings in the two anions are 10.25†(10) and 5.89†(14)°. Inter-molecular O-H⋯O hydrogen bonds link two of the coordinating water mol-ecules to two free CNB anions. In the crystal, further hydrogen-bonding inter-actions are present, namely N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds that link the mol-ecular 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)†à ] may further stabilize the crystal structure.