The crystal structures of salts of N-(4-fluoro­phen­yl)piperazine with four aromatic carb­­oxy­lic acids and with picric acid

The structures are reported for five salts formed by reactions between N-(4-fluoro­phen­yl)piperazine and aromatic acids. In 4-(4-fluoro­phen­yl)piperazin-1-ium 2-fluoro­benzoate monohydrate, C₁₀H₁₄FN₂⁺·C₇H₄FO₂⁻·H₂O, (I), the components are linked by a combination of N—H⋯O and O—H⋯O hydrogen bonds to form a chain of alternating R⁴₆(12) and R⁶₆(16) rings. The ionic components of 4-(4-fluoro­phen­yl)piperazin-1-ium 2-bromo­benzoate 0.353-hydrate, C₁₀H₁₄FN₂⁺·C₇H₄BrO₂⁻·0.353H₂O, (II), are linked by N—H⋯O hydrogen bonds to form a centrosymmetric four-ion aggregate containing an R⁴₄(12) motif, and these aggregates are linked into a mol­ecular ladder by a single C—H⋯π(arene) hydrogen bond. 4-(4-Fluoro­phen­yl)piperazin-1-ium 2-iodo­benzoate, C₁₀H₁₄FN₂⁺·C₇H₄IO₂⁻, (III), crystallizes with Z′ = 2 in space group P: the four independent ions are linked by N—H⋯O hydrogen bonds to form a non-centrosymmetric aggregate again containing an R⁴₄(12) motif, and aggregates of this type are linked into a ribbon by a combination of C—H⋯O and C—H⋯π(arene) hydrogen bonds. The anion in 4-(4-fluoro­phen­yl)piperazin-1-ium 2,4,6-tri­nitro­phenolate, C₁₀H₁₄FN₂⁺·C₆H₂N₃O₇⁻, (IV), shows clear evidence of extensive electronic delocalization from the phenolate O atom into the adjacent ring. The ions are linked by a combination of two-centre N—H⋯O and three-centre N—H⋯(O)₂ hydrogen bonds to form centrosymmetric four-ion aggregates containing three types of ring. The ions in 4-(4-fluoro­phen­yl)piperazin-1-ium 3,5-di­nitro­benzoate, C₁₀H₁₄FN₂⁺·C₇H₃N₂O₆⁻, (V), are again linked by N—H⋯O hydrogen bonds to form centrosymmetric R⁴₄(12) aggregates, which are themselves linked by a C—H⋯π(arene) hydrogen bond to form sheets, the stacking of which leads to the formation of narrow channels, containing disordered and/or mobile solvent entities. Comparisons are made with some related structures.