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

In the title adduct, two 3,5-di­nitro­salicylic acid mol­ecules in the dianionic (DNSA²⁻) form, two protonated piperazine-1,4-diium cations (PIP²⁺) and a neutral piperazine mol­ecule (PIP) along with two water mol­ecules are found in the asymmetric unit. The crystal structure of the title adduct is reported, and hydrogen-bonding inter­actions are discussed.

The crystal structure of the adduct piperazine-1,4-diium 3,5-di­nitro-2-oxidobenzoate–piperazine–water (2/1/2) shows the existence of a 3,5-di­nitro­salicylate dianion (DNSA²⁻) and a protonated piperazine-1,4-diium cation (PIP²⁺) along with a piperazine mol­ecule. The formula of the title adduct in the asymmetric unit is 2C₄H₁₂N₂²⁺·2C₇H₂N₂O₇²⁻·C₄H₁₀N₂·2H₂O with Z = 1. The piperazine ring in the piperazine-1,4-diium cation and in the neutral piperazine mol­ecule adopt chair conformations. All O atoms in the DNSA²⁻ moiety and the water mol­ecule act as hydrogen-bonding acceptors for various inter­molecular O—H⋯O, N—H⋯O and C—H⋯O inter­actions, which stabilize the crystal structure. Various supra­molecular architectures formed by the different inter­molecular inter­actions are discussed. The relative contribution of various inter­molecular 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.