4,4′-Bipyridinium bis­(μ-4-oxo-1,4-dihydropyridine-2,6-dicarboxyl­ato)bis­[aqua­hydroxido­anti­monate(III)] dihydrate

The title compound, (C(10)H(10)N(2))[Sb(2)(C(7)H(2)NO(5))(2)(OH)(2)(H(2)O)(2)]·2H(2)O, consists of a binuclear anion, a diprotonated 4,4′-bipyridinium cation and two uncoordinated water mol­ecules. Each Sb(III) atom is six-coordinated by one chelating 4-oxidopyridine-2,6-dicarboxyl­ate ligand, one water mol­ecule, one OH group and one bridging O atom from a neighboring carboxyl­ate group in a distorted penta­gonal-pyramidal geometry, with the OH group at the apical position. The two pyridine rings in the bipyridinium cation are twisted with respect to each other, making a dihedral angle of 22.7 (1)°. The cations are connected to the anions by N—H⋯O hydrogen bonds, forming a chain. The coordinated water mol­ecules form hydrogen bonds with the oxido O atoms of the anion, building a two-dimensional sheet, which is further connected into a three-dimensional structure by O—H⋯O and C—H⋯O hydrogen bonds and C=O⋯π inter­actions [O⋯centroid distances = 3.1785 (17), 3.4737 (19) and 3.5685 (19) Å].