Further study of (+/-)-mefloquinium chloride solvates. Crystal structures of the hemihydrate and monohydrate of (+/-)-mefloquinium chloride, from data collected at 120 K.

The crystal structure of a monohydrate of (+/-)-mefloquinium chloride, (+/-)-[MEFHCl.(H(2)O)], has been obtained from data collected at 120 K. Further details of the crystal structure of a hemihydrate, (+/-)-[MEFHCl*(1/2)(H(2)O)], previously determined at room temperature, are also reported from data collected at 120 K. The structural data, along with X-ray powder patterns, infrared spectra (both mid and near IR ranges) and DSC data, provide definitive evidence for the two hydrates. Further attempts to completely resolve the crystal structure of a tetragonal solvated phase failed due to the considerable disorder, involving the solvates, either water or methanol, even at 120 K, however X-ray powder pattern and infrared spectral and DSC data for this phase are also reported. Comparisons of the data obtained for the hydrates in this study, with X-ray powder patterns and mid-infrared spectra of previously reported forms of (+/-)-mefloquinium chloride have highlighted erroneous assignments and allowed structural identification of previously and differently designated forms.