Crystal structure of triaqua(4-cyanobenzoato-?2O,O')(nicotinamide-?N1)zinc 4-cyanobenzoate

The asymmetric unit of the title salt, [Zn(C8H4NO2)(C6H6N2O)(H2O)(3)](C8H4NO2), contains one complex cation and one 4-cyanobenzoate (CNB) counter-anion. The Zn II atom in the cation is coordinated by one 4cyanobenzoate 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) degrees. Intermolecular O-H center dot center dot center dot 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 center dot center dot center dot O, O-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds that link the molecular components, enclosing R-2(2) (12), R-3(3) (8) and R3 3 (9) ring motifs and forming layers parallel to (001). pi-pi contacts between benzene rings [centroid-to-centroid distances = 3.791 (1) and 3.882 (1) angstrom] may further stabilize the crystal structure.