Mirogabalin, C₁₂H₁₉NO₂, and mirogabalin besylate, C₁₂H₂₀NO₂⁺·C₆H₅O₃S

The crystal structures of mirogabalin and mirogabalin besylate have been solved and refined using synchrotron powder X-ray diffraction data, and optimized using density functional theory (DFT) techniques. Mirogabalin crystallizes in the space group C2 (No. 5), with a = 12.2850 (4), b = 6.01139 (10), c = 17.6634 (11) Å, β = 100.838 (2)°, V = 1281.17 (8) ų, and Z = 4 at 295 K. Mirogabalin besylate crystallizes in the space group P2₁ (No. 4), with a = 16.4631 (3), b = 9.34335 (5), c = 12.66010 (18) Å, β = 102.2750 (8)°, V = 1902.863 (17) ų, and Z = 4 at 295 K. Both structures are layered, with hydrophilic hydrogen-bonded regions in the centers of the layers. In mirogabalin, zwitterions are linked by intra- and intermolecular N-H...O hydrogen bonds into spiral chains along the b axis, which result in linking the molecules into layers. In the besylate, discrete N-H...O and O-H...O hydrogen bonds link the cations and anions into layers parallel to the bc plane. The powder patterns have been submitted to the ICDD for inclusion in the Powder Diffraction File (PDF).