Bis(μ-3-hydroxy­benzoato)-κ2 O 1:O 3;κ2 O 3:O 1-bis­[bis­(1H-benzimidazole-κN 3)(3-hydroxy­benzoato-κO)nickel(II)] bis­(1H-benzimidazole-κN 3)bis­(3-hy­droxy­benzoato-κO 1)nickel(II) hexa­hydrate

The title compound, [Ni(2)(C(7)H(5)O(3))(4)(C(7)H(6)N(2))(4)][Ni(C(7)H(5)O(3))(2)(C(7)H(6)N(2))(2)]·6H(2)O, is a mononuclear/dinuclear nickel(II) cocrystal, the two mol-ecular species inter-acting through hydrogen bonds that involve the uncoordinated water mol-ecules. In the mononuclear species, the Ni(II) ion, located on an inversion center, is coordinated by two 1H-benzimidazole (bzim) ligands and two 3-hydroxy-benzoate (hba) anions in a square-planar geometry. In the centrosymmetric dinuclear species, the Ni(II) ion is coordinated by two bzim ligands and three hba anions in a square-pyramidal geometry; of the two independent hba anions, one bridges two Ni(II) ions with both carboxylate and hydroxyl groups whereas the other coordin-ates in a unidentate manner to the Ni(II) ion. The apical Ni-O(hydrox-yl) bond is 0.39 Å longer than the basal Ni-O(carbox-yl) bonds. The face-to-face separation of 3.326 (9) Å indicates the existence of π-π stacking between parallel bzim ligands of adjacent dinuclear entities. Extensive N-H⋯O and O-H⋯O hydrogen bonds help to stabilize the crystal structure.