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

The title compound, C(10)H(8)N(2)·2C(7)H(5)NO(4),was obtained unintentionally as the harvested product of the hydro­thermal reaction between Co(OAc)(2)·4H(2)O and 4,4′-bipyridine in the presence of 3-nitro­phthalic acid. In the reaction, 3-nitro­phthalic acid is transformed into 3-nitro­benzoic acid by an in situ deca­rboxylation reaction, in which the carboxyl­ate group is not deprotonated and is uncoordinated. In the crystal, the uncoordinated 3-nitro­benzoic acid and free 4,4′-bipyridine mol­ecules are linked alternately by O—H⋯N hydrogen bonds into chains, which are assembled by C—H⋯O hydrogen bonds into a three-dimensional supra­molecular network.