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

Pressure-promoted formation of intermolecular C−H···O contacts has been rationalized by the electrostatic potential distribution and molecular conformation in tetrahydrofuran, C<sub>4</sub>H<sub>8</sub>O. 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 <i>C</i>2/<i>c</i>. The sequence of C−H···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···O contacts short enough to be classified as hydrogen bonds in the compressed crystal.