The crystal structure of tafamidis has been independently resolved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Tafamidis crystallizes in space group P21/c (#14) with a = 3.787093(6), b = 14.97910(4), c = 22.93751(7) Å, β = 90.92672(19)°, V = 1,301.012(4) Å3, and Z = 4 at 295 K. The crystal structure consists of stacks of molecules along the a-axis. The molecules are inclined to this axis; the mean plane is (−4, 2, 11). Strong centrosymmetric O–H⋅⋅⋅O hydrogen bonds exist between carboxylic acid groups. The molecules are linked along the b-axis by C–H⋅⋅⋅N hydrogen bonds. Two C–H⋅⋅⋅Cl hydrogen bonds also 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®).
