The crystal structures and Hirshfeld surface analyses of three salts of 1-(4-nitrophenyl)piperazine with 2-chlorobenzoic acid, 2-bromobenzoic acid and 2-iodobenzoic acid are reported. The chlorobenzoate salt, C10H14N3O2 +·C7H4ClO2 −, contains whole-ion-disordered cations and anions, which were modeled with two equivalent conformations with occupancies of 0.745 (10)/0.255 (10) and 0.563 (13)/0.437 (13), respectively. The bromobenzoate and iodobenzoate derivatives are isomorphous and crystallize as hemihydrates, viz. C10H14N3O2 +·C7H4BrO2 −·0.5H2O and C10H14N3O2 +·C7H4IO2 −·0.5H2O, respectively [the water molecule is disordered over two locations with occupancies of 0.276 (3)/0.223 (3) for the iodobenzoate derivative]. In the extended structures, all three salts feature an R 4 4(12) loop of two anions and two cations linked by N—H...O hydrogen bonds.
