High-Pressure Polymorphism of Ribavirin.

The effect of high pressure on ribavirin, a broad-spectrum antiviral consisting of ribofuranosyl triazole, and carboxamide moieties, has been studied up to ∼10 GPa. Three new high-pressure phases, designated , and , have been obtained by compression of the ambient-pressure form with structures refined up to 7.5 GPa. The new phases are formed at 5.3, 6.0, and 7.2 GPa, respectively, and crystallize in space group 222 with ' = 3, 1, and 1. They are distinguished by changes in the conformation of the ribofuranosyl moiety which impacts both the molecular geometry and the supramolecular structure.