| Summary: | The title compound, [Ni2(C7H5O3)4(C7H6N2)4][Ni(C7H5O3)2(C7H6N2)2]·6H2O, is a mononuclear/dinuclear nickel(II) cocrystal, the two molecular species interacting through hydrogen bonds that involve the uncoordinated water molecules. In the mononuclear species, the NiII ion, located on an inversion center, is coordinated by two 1H-benzimidazole (bzim) ligands and two 3-hydroxybenzoate (hba) anions in a square-planar geometry. In the centrosymmetric dinuclear species, the NiII 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 NiII ions with both carboxylate and hydroxyl groups whereas the other coordinates in a unidentate manner to the NiII ion. The apical Ni—Ohydroxyl bond is 0.39 Å longer than the basal Ni—Ocarboxyl 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.
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