trans-Tetra­aqua­bis­(isonicotinamide-κN (1))nickel(II) bis­(3-hy­droxy­benzoate) tetra­hydrate

The asymmetric unit of the title compound, [Ni(C(6)H(6)N(2)O)(2)(H(2)O)(4)](C(7)H(5)O(3))(2)·4H(2)O, contains one-half of the complex cation with the Ni(II) ion located on an inversion center, a 3-hy­droxy­benzoate counter-anion and two uncoordinated water mol­ecules. Four water O atoms in the equatorial plane around the Ni(II) ion [Ni—O = 2.052 (2) and 2.079 (2) Å] form a slightly distorted square-planar arrangement, which is completed up to a distorted octa­hedron by the two N atoms [Ni—N = 2.075 (3) Å] from two isonicotinamide ligands. In the anion, the carboxyl­ate group is twisted from the attached benzene ring by 8.8 (3)°. In the crystal, a three-dimensional hydrogen-bonding network, formed by classical O—H⋯O and N—H⋯O hydrogen bonds, consolidates the crystal packing, which also exhibits π–π inter­actions between the benzene and pyridine rings, with centroid–centroid distances of 3.455 (2) and 3.621 (2) Å, respectively.