Syntheses, crystal structures and Hirshfeld surface analysis of three salts of 1-(4-nitrophenyl)piperazine

The structures and Hirshfeld surface analysis of three salts of 1-(4-nitrophenyl)piperazine are discussed. In 4-(4-nitrophenyl)piperazin-1-ium salicylate (C10H14N3O2+ · C7H5O3 − ), there are strong hydrogen bonds between cation and anion and the 4-nitrophenyl substituent occupies an equatorial position in the piperazinium ring. The cation and anion are linked together by supramolecular interactions [graph-set notation of hydrogen bonding C_{2}^{2}(6) propagating in the a-axis direction]. Additionally, there is π – π stacking involving the salicylate anion and the piperazinium cation in adjacent asymmetric units as well as a C — H... π interaction between a hydrogen atom on the piperazine ring and the phenyl ring within the salicyclate anion. In bis[4-(4-nitrophenyl)piperazin-1-ium] bis(4-fluorobenzoate) trihydrate (2C10H14N3O2+ · 2C7H4FO2 − · 3H2O), there are two cations, two anions, and three water molecules of solvation in the asymmetric unit, all linked by hydrogen bonds [graph-set notation of hydrogen bonding R22(20) between adjacent cations and R33(9) between a cation and its adjacent anion]. In the anion, the 4-nitrophenyl ring occupies an axial substitution position in the piperazinium ring, which is relatively rare. Within the asymmetric unit, the phenyl groups in the cations show an offset π – π interaction. Additionally, there is a C — H... π interaction between a hydrogen atom on the phenyl ring within a cation and the phenyl ring within an ani...
Source: Acta Crystallographica Section E - Category: Chemistry Authors: Tags: crystal structure piperazinium salt Hirshfeld surface analysis salicylate graph-set notation axial and equatorial substitution patterns in piperazinium rings research communications Source Type: research