The structure of methanol at 5.09 GPa: the fortuitous formation of a new high-pressure phase

Abstract

The crystal structure of a new polymorph of methanol (the ε polymorph) has been determined at 5.09 GPa by single crystal X-ray diffraction. The polymorph crystallises in the monoclinic space group, P2₁/c, with twelve molecules in the unit cell, and exhibits a 4-membered hydrogen bonded ring structure, never previously observed in any crystal structure of methanol. The ε phase was also serendipitously seeded by the presence of another crystallite, giving rise to suitable crystallisation conditions 2 GPa lower than previously reported.