Rubidium 2,4,6-trioxo-1,3-diazinan-5-ide-1,3-diazinane-2,4,6-trione-water(1/1/1)

The asymmetric unit of the title compound, Rb(+)center dot C(4)H(3)N(2)O(3)(-)center dot C(4)H(4)N(2)O(3)center dot H(2)O, consists of one rubidium cation, a barbituric acid molecule, a barbiturate anion and one water molecule. The rubidium ion has seven close-contact interactions with O atoms, with Rb center dot center dot center dot O distances ranging from 2.8594 (16) to 3.2641 (14) angstrom. These seven O atoms together with an eighth O atom at 3.492 (2) angstrom away from Rb form a distorted polyhedron with shape intermediate between an antiprism and a dodecahedron. The Rb(+) ions connect layers built of organic components and water molecules linked via N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds.