Structural study of hexaiodobenzene up to 9.7 GPa

The crystal and molecular structures of hexaiodobenzene (C6I6) have been in vestigated 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(1)/c, which was observed at atmospheric pressure. A 25.5% compression in volume at 9.7 GPa involves remarkable decr eases 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 i odine atoms to be suspended from an average plane of the molecule. Such a t ransformation enhances the intermolecular charge transfer interaction.