Omadacycline dihydrate, C29H40N4O7·2H2O, from X-ray powder diffraction data

The crystal structure of the title compound {systematic name: (4S,4aS,5aR,12aR)-4,7-bis(dimethylamino)-9-[(2,2-dimethylpropylamino)methyl]-1,10,11,12a-tetrahydroxy-3,12-dioxo-4a,5,5a,6-tetrahydro-4H-tetracene-2-carboxamide dihydrate, C29H40N4O7·2H2O} has been solved and refined using synchrotron X-ray powder diffraction data: it crystallizes in space group R3 with a = 24.34430 (7), c = 14.55212 (4) Å, V = 7468.81 (2) Å3 and Z = 9. Most of the hydrogen bonds are intramolecular, but two classical N—H...O intermolecular hydrogen bonds (along with probable weak C—H...O and C—H...N hydrogen bonds) link the molecules into a three-dimensional framework. The framework contains voids, which contain disordered water molecules. Keto–enol tautomerism is apparently important in this molecule, and the exact molecular structure is ambiguous.