4-Acetyl-piperazinium picrate.

In the title salt, C6H13N2O(+)·C6H2N3O7 (-) (systematic name: 4-acetyl-piperazin-1-ium 2,4,6-tri-nitro-phenolate), the piperazin-1-ium ring has a slightly distorted chair conformation. In the picrate anion, the mean planes of the two o-NO2 and p-NO2 groups are twisted with respect to the benzene ring by 15.0 (2), 68.9 (4) and 4.4 (3)°, respectively. In the crystal, N-H⋯O hydrogen bonds are observed, linking the ions into an infinite chain along [010]. In addition, weak cation-anion C-H⋯O inter-molecular inter-actions and a weak π-π stacking inter-action between the benzene rings of the anions, with an inter-centroid distance of 3.771 (8) Å, help to stabilize the crystal packing, giving an overall sheet structure lying parallel to (100). Disorder was modelled for one of the O atoms in one of the o-NO2 groups over two sites with an occupancy ratio of 0.57 (6):0.43 (6).