Crystal Structure and Thermal Properties of Phenibut, Phenibut H 2 O and Phenibut HCl: a Case for Phase Stability Based on Structural Considerations

Phenibut is an anxiolytic drug approved for medical use in many eastern European states. With the exception of the HCl Salt of Phenibut no crystal structure related research has been conducted on this substance. Herein, the crystal structures of Phenibut and Phenibut⋅H 2 O are presented, including crystal packing analysis based on interaction energy calculations. IR spectra are shown alongside powder diffraction data and thermogravimetric analysis to characterize and compare structural as well as thermal properties of the examined Phenibut forms. Single crystal diffraction is used in conjunction with Crystal Explorer based Hirshfeld analysis to carefully identify the bonding interaction properties in each compound. Finally, a case is made regarding stability of the compared crystalline phases based on the conducted structural analyses and the quantification of the molecular interaction energies.