The structures of eleven (4-phen­yl)piperazinium salts containing organic anions

Eleven (4-phen­yl)piperazinium salts containing organic anions have been prepared and structurally characterized, namely, 4-phenyl­piperazin-1-ium 4-fluoro­benzoate monohydrate, C(10)H(15)N(2) (+)·C(7)H(4)FO(2) (−)·H(2)O, 1; 4-phenyl­piperazin-1-ium 4-bromo­benzoate monohydrate, C(10)H(15)N(2) (+)·C(7)H(4)BrO(2) (−)·H(2)O, 3; 4-phenyl­piperazin-1-ium 4-iodo­benzoate, C(10)H(15)N(2) (+)·C(7)H(4)IO(2) (−), 4; 4-phenyl­piperazin-1-ium 4-nitro­benzoate, C(10)H(15)N(2) (+)·C(7)H(4)NO(4) (−), 5; 4-phenyl­piperazin-1-ium 3,5-di­nitro­salicylate, C(10)H(15)N(2) (+)·C(7)H(3)N(2)O(7) (−), 6; 4-phenyl­piperazin-1-ium 3,5-di­nitro­benzoate, C(10)H(15)N(2) (+)·C(7)H(3)N(2)O(6) (−), 7; 4-phenyl­piperazin-1-ium picrate, C(10)H(15)N(2) (+)·C(6)H(2)N(3)O(7) (−), 8; 4-phenyl­piperazin-1-ium benzoate monohydrate, C(10)H(15)N(2) (+)·C(7)H(5)O(2) (−)·H(2)O, 9; 4-phenyl­piperazin-1-ium p-toluene­sulfonate, C(10)H(15)N(2) (+)·C(7)H(7)O(3)S(−), 10; 4-phenyl­piperazin-1-ium tartarate monohydrate, C(10)H(15)N(2) (+)·C(4)H(5)O(6) (−)·H(2)O, 11; and 4-phenyl­piperazin-1-ium fumarate, C(10)H(15)N(2) (+)·C(4)H(3)O(4) (−), 12. Compounds 1 and 3–12 are all 1:1 salts with the acid proton transferred to the phenyl­piperaizine basic N atom (the secondary amine) with the exception of 3 where there is disorder in the proton position with it being 68% attached to the base and 32% attached to the acid. Of the structures with similar stoichiometries only 3 and 9 are isomorphous. The 4-phenyl substituent in all cases occupies an equatorial position except for 12 where it is in an axial position. The crystal chosen for structure 7 was refined as a non-merohedral twin. There is disorder in 5, 6, 10 and 11. For both 5 and 6, a nitro group is disordered and was modeled with two equivalent orientations with occupancies of 0.62 (3)/0.38 (3) and 0.690 (11)/0.310 (11), respectively. For 6, 10 and 11, this disorder is associated with the phenyl ring of the phenyl­piperazinium cation with occupancies of 0.687 (10)/0.313 (10), 0.51 (7)/0.49 (7) and 0.611 (13)/389 (13), respectively. For all salts, the packing is dominated by the N—H⋯O hydrogen bonds formed by the cation and anion. In addition, several structures contain C—H⋯π (1, 3, 4, 8, 9, 10, and 12) and aromatic π–π stacking inter­actions (6 and 8) and one structure (5) contains a –NO(2)⋯π inter­action. For all structures, the Hirshfeld surface fingerprint plots show the expected prominent spikes as a result of the N—H⋯O and O—H⋯O hydrogen bonds.