4,4′-Bipyridinium bis-(2-carboxypyridine-3-carboxylate)

Abstract

The title salt, C10H10N22+·2C7H4NO4- or (4,4′-bpyH2)(py-2,3-dcH)2, prepared by the reaction between pyridine-2,3-dicarboxylic acid (py-2,3-dcH2) and 4,4′-bipyridine (4,4′-bpy), consists of two anions and one centrosymmetric dication. In the crystal, there are two strong O - H⋯O hydrogen bonds involving the two carboxyl-ate groups, with an O⋯O distance of 2.478 (1) Å, and an N - H⋯N hydrogen bond between the anion and cation, with an N⋯N distance of 2.743 (1) Å. These inter-actions, along with other O - H⋯O and C - H⋯O hydrogen bonds, π-π stacking [centroid-centroid distances 3.621 (7) and 3.612 (7) Å] and ion pairing, lead to the formation of the three-dimensional structure.