Syntheses, crystal structures and Hirshfeld surface analysis of 4-(4-nitro­phen­yl)piperazin-1-ium tri­fluoro­acetate and 4-(4-nitro­phen­yl)piperazin-1-ium tri­chloro­acetate

The synthesis and crystal structures of the mol­ecular salts of 4-(4-nitro­phen­yl)piperazine with tri­fluoro­acetate, namely, 4-(4-nitro­phen­yl)piperazin-1-ium tri­fluoro­acetate, C(10)H(14)N(3)O(2) (+)·C(2)F(3)O(2) (−) (I), and with tri­chloro­acetate, namely, 4-(4-nitro­phen­yl)piperazin-1-ium tri­chloro­acetate, C(10)H(14)N(3)O(2) (+)·C(2)Cl(3)O(2) (−), (II), are reported and compared. A partial positional disorder of the anions was found. In both structures, the piperazine rings adopt a chair conformation, whereas the positions of the nitro­phenyl group on the piperazine ring differ from bis­ectional in (I) to equatorial in (II). In both structures, the supra­molecular assemblies are mono-periodic on the basis of the chain-of-rings motifs supported by aromatic π–π inter­actions. Hirshfeld surface analysis was used to explore the inter­molecular close contacts in both crystals. The most dominant contacts of the Hirshfeld surface of the cation–anion pairs of the asymmetric units are O⋯H/H⋯O, and those with a contribution of halogen atoms: F⋯H/H⋯F in (I) and Cl⋯H/H⋯Cl in (II), respectively.