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

Twelve 4-(4-meth-oxy-phen-yl)piperazin-1-ium salts containing organic anions have been prepared and structurally characterized. The monohydrated benzoate, 4-fluoro-benzoate, 4-chloro-benzoate and 4-bromo-benzoate salts, CHNO·CHO ·HO (I), CHNO·CHFO ·HO (II), CHNO·CHClO ·HO (III), and CHNO·CHBrO ·HO (IV), respectively, are isomorphous and all exhibit disorder in the 4-meth-oxy-phenyl unit: the components are linked by N-H⋯O and O-H⋯O hydrogen bond to form chains of rings. The unsolvated 2-hy-droxy-benzoate, pyridine-3-carboxyl-ate and 2-hy-droxy-3,5-di-nitro-benzoate salts, CHNO·CHO (V), CHNO·CHNO (VI) and CHNO·CHNO (VII), respectively, are all fully ordered: the components of (V) are linked by multiple N-H⋯O hydrogen bonds to form a chain of rings; those of (VI) are linked into a three-dimensional framework by a combination of N-H⋯O, C-H⋯O and C-H⋯N hydrogen bonds and those of (VII), where the anion has a structure reminiscent of the picrate anion, are linked into a three-dimensional array by N-H⋯O and C-H⋯O hydrogen bonds. The hydrogensuccinate and hydrogenfumarate salts, CHNO·CHO (VIII) and CHNO·CHO (IX), respectively, are isomorphous, and both exhibit disorder in the anionic component: N-H⋯O and O-H⋯O hydrogen bonds link the ions into sheets, which are further linked by C-H⋯π(arene) inter-actions. The anion of the hydrogenmaleate salt, CHNO·CHO (X), contains a very short and nearly symmetrical O⋯H⋯O hydrogen bond, and N-H⋯O hydrogen bonds link the anions into chains of rings. The ions in the tri-chloro-acetate salt, CHNO·CClO (XI), are linked into simple chains by N-H⋯O hydrogen bonds. In the hydrated chloranilate salt, 2CHNO·CClO ·2HO (XII), which crystallizes as a non-merohedral twin, the anion lies across a centre of inversion in space group 2/, and a combination of N-H⋯O and O-H⋯O hydrogen bonds generates complex sheets. Comparisons are made with the structures of some related compounds.