Bis(2,6-diamino-pyridinium) hydrogen phthalate nitrate monohydrate.

The title hydrated salt, 2C(5)H(8)N(3) (+)·C(8)H(5)O(4) (-)·NO(3) (-)·H(2)O, was obtained fortuitously from the reaction between 2,6-diamino-pyridine, phthalic acid and Co(NO(3))(2)·6H(2)O at 343 K. The asymmetric unit consists of two crystallographically independent 2,6-diamino-pyridinium cations, a hydrogen phthalate anion, a nitrate ion and a water mol-ecule of crystallization which in the crystal structure are linked by inter-molecular O-H⋯O and N-H⋯O hydrogen bonds into a three-dimensional network. In the hydrogen phthalate anion, there is a very strong intra-molecular O-H⋯O hydrogen bond.