Potassium oxalurate monohydrate.

The title salt, poly[aqua-μ(3)-oxalurato-potassium(I)], K(C(3)H(3)N(2)O(4))(H(2)O), which was obtained from a water solution of oxaluric acid and KOH at room temperature, crystallizes as potassium and oxalurate ions along with a water mol-ecule. The K(+) cation lies on a crystallographic twofold rotation axis (site symmetry 2, Wyckoff position f), and the water and oxalurate mol-ecules are located within different mirror planes (site symmetry m, Wyckoff position g). The K(+) cation is eight-coordinated by six O atoms of six oxalurate ligands and two O atoms from two water mol-ecules in a distorted square-anti-prismatic geometry. All of the eight coordinated O atoms are in a monodentate bridging mode, with alternate bridged K⋯K distances of 3.5575 (12) and 3.3738 (12) Å. The oxalurate ligand shows a μ(3)-bridging coordination mode, which links the K(+) cation into a three-dimensional network. The oxalurate ligands and the water mol-ecules are involved in inter- and intra-molecular N-H⋯O, and O-H⋯O hydrogen bonds, which stabilize the network.