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—HO and O—HO hydrogen bonds to form a chain of alternating R4 6(12) and R6 6(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—HO hydrogen bonds to form a centrosymmetric four-ion aggregate containing an R4 4(12) motif, and these aggregates are linked into a molecular ladder by a single C—H(arene) hydrogen bond. 4-(4-Fluorophenyl)piperazin-1-ium 2-iodobenzoate, C10H14FN2 + C7H4IO2 , (III), crystallizes with Z0 = 2 in space group P1: the four independent ions are linked by N—HO hydrogen bonds to form a non-centrosymmetric aggregate again containing an R4 4(12) motif, and aggregates of this type are linked into a ribbon by a combination of C— HO and C—H(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— HO 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—HO hydrogen bonds to form centrosymmetric R4 4(12) aggregates, which are themselves linked by a C—H(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.