Three 4-(4-fluoro-phen-yl)piperazin-1-ium salts containing organic anions: supra-molecular assembly in one, two and three dimensions.

Three salts containing the 4-(4-fluoro-phen-yl)piperazin-1-ium cation have been prepared and structurally characterized. In 4-(4-fluoro-phen-yl)piperazin-1-ium 2-hy-droxy-3,5-di-nitro-benzoate, CHFN ·CHNO , (I), the anion contains an intra-molecular O-H⋯O hydrogen bond, and it has a structure similar to that of the picrate ion. The cations and anions are linked into [001] chains of rings by a combination of two three-centre N-H⋯(O) hydrogen bonds. The anion in 4-(4-fluoro-phen-yl)piperazin-1-ium hydrogen oxalate, CHFN ·CHO , (II), is planar, and the cations and anions are linked into (100) sheets by multiple hydrogen bonds including two-centre N-H⋯O, three-centre N-H⋯(O), O-H⋯O, C-H⋯O and C-H⋯π(arene) types. In 4-(4-fluoro-phen-yl)piperazin-1-ium hydrogen (2,3)-tartrate monohydrate, CHFN ·CHO ·HO, (III), the anion exhibits an approximate non-crystallographic twofold rotation symmetry with anti-periplanar carboxyl groups. A combination of eight hydrogen bonds, encompassing two- and three-centre N-H⋯O systems, O-H⋯O and C-H⋯π(arene) types, link the independent components into a three-dimensional framework. Comparisons are made with some related structures.