Crystal structure and Hirshfeld surface analysis of the hydrated 2:1 adduct of piperazine-1,4-diium 3,5-di-nitro-2-oxidobenzoate and piperazine.

The crystal structure of the adduct piperazine-1,4-diium 3,5-di-nitro-2-oxidobenzoate-piperazine-water (2/1/2) shows the existence of a 3,5-di-nitro-salicylate dianion (DNSA) and a protonated piperazine-1,4-diium cation (PIP) along with a piperazine mol-ecule. The formula of the title adduct in the asymmetric unit is 2CHN ·2CHNO ·CHN·2HO with = 1. The piperazine ring in the piperazine-1,4-diium cation and in the neutral piperazine mol-ecule adopt chair conformations. All O atoms in the DNSA moiety and the water mol-ecule act as hydrogen-bonding acceptors for various inter-molecular O-H⋯O, N-H⋯O and C-H⋯O inter-actions, which stabilize the crystal structure. Various supra-molecular architectures formed by the different inter-molecular inter-actions are discussed. The relative contribution of various inter-molecular contacts is analysed with the aid of two-dimensional (full and decomposed) fingerprint plots, indicating that H⋯O/O⋯H (50.2%) and H⋯H (36.2%) contacts are the major contributors to the stabilization of the crystal structure.