2-Isopropyl-6-methyl-4-oxo-3,4-dihydro­pyrimidin-1-ium 2-carb­oxy-4,6-dinitro­phenolate monohydrate

In the title mol­ecular salt, C(8)H(13)N(2)O(+)·C(7)H(3)N(2)O(7) (−)·H(2)O, the pyrimidinium cation is essentially planar, with a maximum deviation of 0.009 (1) Å. The cation undergoes an enol–keto tautomerism during the crystallization. In the crystal, the ion pairs and water mol­ecules are connected via O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds, forming two-dimensional networks parallel to the bc plane. There is an intra­molecular O—H⋯O hydrogen bond in the 3,5-dinitro­salicylate anion, which generates an S(6) ring motif.