Diaquabis(4-formylbenzoato-κO¹)bis(nicotinamide- κN¹)nickel(II)

In the title complex, [Ni(C₈H₅O₃) ₂(C₆H₆N₂O)₂(H ₂O)₂], the Ni^II cation is located on an inversion center and is coordinated by two 4-formylbenzoate (FB) anions, two nicotinamide (NA) ligands and two water molecules. The four O atoms in the equatorial plane around the Ni^II cation form a slightly distorted square-planar arrangement, while the slightly distorted octahedral coordination is completed by the two N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxylate group and the adjacent benzene ring is 23.67 (8)°, while the pyridine and benzene rings are oriented at an angle of 89.04 (4)°. The coordinating water molecule links with the carboxylate group via an O - H⋯O hydrogen bond. In the crystal, N - H⋯O, O - H⋯O and weak C - H⋯O hydrogen bonds link the molecules into a three-dimensional supramolecular network. π-π contacts between benzene rings [centroid-centroid distance = 3.8414 (7) Å] may further stabilize the structure. A weak C - H⋯π interaction also occurs.