catena-Poly[4,4′-bipyridinium [[diaqua­disulfatocadmium(II)]-μ-4,4′-bipyridine-κ(2) N:N′] dihydrate]

The title compound, {(C(10)H(10)N(2))[Cd(SO(4))(2)(C(10)H(8)N(2))(H(2)O)(2)]·2H(2)O}(n), consists of anionic chains of the Cd complex, diprotonated 4,4′-bipyridinium cations and uncoordinated water mol­ecules. In the anionic chain, the Cd atom lies on a center of inversion in an octa­hedral geometry. The midpoint of the coordinated bipyridine also resides on a center of inversion, as does the non-coordinated bipyridinium counterion. O—H⋯O and N—H⋯O hydrogen bonding inter­actions and π–π stacking inter­actions in the structure are responsible for the supra­molecular assembly.