Chloride salts of the antibacterial agent pazufloxacin: (H ₃ O) ₂ (Pzfx) ₅ Cl ₇ ·10H ₂ O and (Pzfx)Cl·1.75H ₂ O·0.5C ₂ H ₅ OH

Recrystallization of pazufloxacinium mesylate from HCl solutions yielded two previously unknown salts of pazufloxacin. These were characterized by X-ray diffraction and are bis(oxidanium) pentakis[(2S)-6-(1-azaniumylcyclopropyl)-7-fluoro-2-methyl-10-oxo-4-oxa-1-azatricyclo[7.3.1.0^5,13]trideca-5(13),6,8,11-tetraene-11-carboxylic acid] heptachloride decahydrate, 2H₃O⁺·5C₁₆H₁₆FN₂O₄⁺·7Cl^-·10H₂O (1), and (2S)-6-(1-azaniumylcyclopropyl)-7-fluoro-2-methyl-10-oxo-4-oxa-1-azatricyclo[7.3.1.0^5,13]trideca-5(13),6,8,11-tetraene-11-carboxylic acid chloride ethanol hemisolvate 1.75-hydrate, C₁₆H₁₆FN₂O₄⁺·Cl^-·0.5C₂H₆O·1.75H₂O (2), which were obtained from acetonitrile and ethanol, respectively. The compounds crystallize in the noncentrosymmetric triclinic space group P1. Salt 1 contains five independent cations and seven chloride anions, while compound 2 contains eight independent cations and anions. In both, an intramolecular COOH...O=C hydrogen bond is present and the amino group is protonated. The cations, anions and solvent molecules form extensive hydrogen-bonded frameworks. In addition, in both structures, the cations are packed into infinite stacks via π-π interactions, with interplanar distances of approximately 3.2 Å.