4,4′-Bipyridine–butane-1,2,3,4-tetra­carboxylic acid (1/1)

The title compound, C(10)H(8)N(2)·C(8)H(10)O(8), is an example of a system with a short O⋯H⋯N hydrogen bond [O⋯N = 2.565 (3) Å]. The crystal structure comprises a 1:1 adduct between 4,4'-bipyridine and butane-1,2,3,4-tetra-carboxylic acid, where both components are centrosymmetric. The component mol-ecules are linked through strong O⋯H⋯N hydrogen bonds, forming chains extending approximately along [11]. The chains are inter-connected by O⋯H⋯O hydrogen bonds and weak stacking inter-actions involving the pyridyl rings of the 4,4'-bipyridine mol-ecules [centroid-centroid distance = 3.73 (2) Å and inter-planar distance = 3.35 (1) Å]. The H atom of the short O⋯H⋯N hydrogen bond is disordered over two positions with site occupancy factors of ca 0.6 and 0.4. One methylene group is disordered over two positions; the site occupancy factors are ca 0.9 and 0.1.