Pressure-Generated Hydrogen Bonds and the Role of Subtle Molecular Features in Tetrahydrofuran

Pressure-promoted formation of intermolecular C-H center dot center dot center dot O contacts has been rationalized by the electrostatic potential distribution and molecular conformation in tetrahydrofuran, C4H8O. Its isochoric crystallization at 2.25, 3.26, and 3.80 GPa and isobaric freezing at ambient pressure lead to a monoclinic phase, space group C2/c. The sequence of C-H center dot center dot center dot O distances in these structures is consistent with the electrostatic potential distribution and favored acceptor directionality for hydrogen atoms. The pressure evolution of intermolecular interactions increases the number of C-H center dot center dot center dot O contacts short enough to be classified as hydrogen bonds in the compressed crystal.