Abstract: | The title compound, C4H10N3O2+·C2H2NO3−·C2H3NO3, contains at least 11 distinct hydrogen‐bond interactions showing a great variety of bond strengths. The shortest and strongest hydrogen bond O...O = 2.5004 (12) Å] is found between the uncharged oxamic acid molecule and the oxamate monoanion. The grouping formed by such a strong hydrogen bond can thus be considered as a hydrogen bis(oxamate) monoanion. It lacks crystallographic symmetry and the two oxamate groups have different conformations, showing an asymmetric hydrogen‐bond interaction. Significantly, the asymmetry allows us to draw a direct comparison of site basicity for the two inequivalent carboxylate O atoms in the planar oxamate anion. The constituent molecular ions of (I) form ribbons, where all amide and carboxylate groups are coplanar. Graph‐set analysis of the hydrogen‐bonded networks reveals the R22(10) and R22(9) homodromic nets as important structure‐directing motifs, which appear to be a common feature of many oxamate‐containing compounds. |