2-Amino-5-chloropyridin-1-ium barbiturate dihydrate

In the title hydrated salt, C 5 H 6 ClN 2 + ·C 4 H 3 N 2 O 3 − ·2H 2 O, the asymmetric unit contains two cations, two anions and four water molecules of crystallization. In the extended structure, the barbiturate (2,4,6-trioxo-1,3-diazinan-5-ide) anions form a wave-like supramolecular [001] chain decorated by the cations, mediated by numerous N—H...O hydrogen bonds. Adjacent chains are cross-linked by [010] chains of water molecules featuring four- and six-membered rings and five-membered carboxylate aggregates via O—H...O hydrogen bonds.