Structural study of hexaiodobenzene up to 9.7 GPa

The crystal and molecular structures of hexaiodobenzene $\left({\mathrm{C}}_6{\mathrm{I}}_6\right)$ have been investigated at high pressure up to 9.7 GPa and at room temperature by x-ray powder diffraction technique. The crystal structure under pressure up to 9.7 GPa maintained its monoclinic ${P2\mathrm{}}_1/c,$ which was observed at atmospheric pressure. A 25.5% compression in volume at 9.7 GPa involves remarkable decreases in the b-axis length and intermolecular I-I distances among adjacent molecules located on the b axis and a bc plane. Pressurization causes six iodine atoms to be suspended from an average plane of the molecule. Such a transformation enhances the intermolecular charge transfer interaction.