Crystal structure and Hirshfeld surface analysis of 1,2,4-triazolium hydrogen oxalate

The asymmetric unit of the title 1:1 salt 1,2,4-triazolium hydrogen oxalate, C(2)H(4)N(3) (+)·C(2)HO(4) (−) (I), comprises one 1,2,4-triazolium cation and one hydrogen oxalate anion. In the crystal, the hydrogen oxalate anions are linked by O—H⋯O hydrogen bonds into chains running parallel to [100]. In turn, the anionic chains are linked through the 1,2,4-triazolium cations by charge-assisted (+)N—H⋯O(−) hydrogen bonds into sheets aligned parallel to (01[Image: see text]). The sheets are further stacked through π–π inter­actions between the 1,2,4-triazolium rings [centroid-to-centroid distance = 3.642 (3) Å, normal distance = 3.225 (3) Å, slippage 1.691 Å], resulting in the formation of a three-dimensional supra­molecular network. Hirshfeld surface analysis of the title salt suggests that the most significant contributions to the crystal packing are by H⋯O/O⋯H and H⋯N/N⋯H contacts involving the hydrogen bonds.