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, C(10)H(14)FN(2) (+)·C(7)H(4)FO(2) (−)·H(2)O, (I), the components are linked by a combination of N—H⋯O and O—H⋯O hydrogen bonds to form a chain of alternating R (4) (6)(12) and R (6) (6)(16) rings. The ionic components of 4-(4-fluoro­phen­yl)piperazin-1-ium 2-bromo­benzoate 0.353-hydrate, C(10)H(14)FN(2) (+)·C(7)H(4)BrO(2) (−)·0.353H(2)O, (II), are linked by N—H⋯O hydrogen bonds to form a centrosymmetric four-ion aggregate containing an R (4) (4)(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, C(10)H(14)FN(2) (+)·C(7)H(4)IO(2) (−), (III), crystallizes with Z′ = 2 in space group P [Image: see text]: the four independent ions are linked by N—H⋯O hydrogen bonds to form a non-centrosymmetric aggregate again containing an R (4) (4)(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, C(10)H(14)FN(2) (+)·C(6)H(2)N(3)O(7) (−), (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, C(10)H(14)FN(2) (+)·C(7)H(3)N(2)O(6) (−), (V), are again linked by N—H⋯O hydrogen bonds to form centrosymmetric R (4) (4)(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.