A proposed crystal structure of delamanid, C ₂₅ H ₂₅ F ₃ N ₄ O ₆

Abstract The crystal structure of delamanid has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. Solution and refinement of the structure presented significant difficulties, and the result should be considered proposed or approximate. Delamanid crystallizes in the space group P2 1 2 1 2 1 (#19) with a = 67.3701(18), b = 12.86400(9), c = 5.65187(12) Å, V = 4,898.19(14) Å 3 , and Z = 8 at 295 K. There are two independent delamanid molecules, with different conformations, which are essentially identical in energy. The crystal structure consists of layers of delamanid molecules perpendicular to the a -axis. The imidazooxazole ring systems stack along the b -axis, and the trifluoromethyl groups make up the boundaries of the corrugated layers. There are no classical hydrogen bonds in the crystal structure. Eight C–H···O and one C–H···N hydrogen bonds contribute to the lattice energy. The powder pattern has been submitted to the International Centre for Diffraction Data for inclusion in the Powder Diffraction File ™ (PDF ® ).