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, C₁₀H₁₄N₃O₂⁺·C₂F₃O₂^- (I), and with trichloroacetate, namely, 4-(4-nitrophenyl)piperazin-1-ium trichloroacetate, C₁₀H₁₄N₃O₂⁺·C₂Cl₃O₂^-, (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. [ABSTRACT FROM AUTHOR]