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

Abstract

Eleven (4-phenyl)piperazinium salts containing organic anions have been prepared and structurally characterized, namely, 4-phenylpiperazin-1-ium 4-fluorobenzoate monohydrate, C10H15N2 +·C7H4FO2 −·H2O, 1; 4-phenylpiperazin-1-ium 4-bromobenzoate monohydrate, C10H15N2 +·C7H4BrO2 −·H2O, 3; 4-phenylpiperazin-1-ium 4-iodobenzoate, C10H15N2 +·C7H4IO2 −, 4; 4-phenylpiperazin-1-ium 4-nitrobenzoate, C10H15N2 +·C7H4NO4 −, 5; 4-phenylpiperazin-1-ium 3,5-dinitrosalicylate, C10H15N2 +·C7H3N2O7 −, 6; 4-phenylpiperazin-1-ium 3,5-dinitrobenzoate, C10H15N2 +·C7H3N2O6 −, 7; 4-phenylpiperazin-1-ium picrate, C10H15N2 +·C6H2N3O7 −, 8; 4-phenylpiperazin-1-ium benzoate monohydrate, C10H15N2 +·C7H5O2 −·H2O, 9; 4-phenylpiperazin-1-ium p-toluenesulfonate, C10H15N2 +·C7H7O3S−, 10; 4-phenylpiperazin-1-ium tartarate monohydrate, C10H15N2 +·C4H5O6 −·H2O, 11; and 4-phenylpiperazin-1-ium fumarate, C10H15N2 +·C4H3O4 −, 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 –NO2...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.