Structural change of iodanil under high pressure

Crystal structures of tetraiodo-p-benzoquinone (iodanil) up to 10.3 GPa were measured by x-ray powder diffraction experiments at room temperature to investigate the mechanism of pressure-induced metallization of iodanil. Diffraction patterns analyzed by the Rietveld method were well explained with the space group P21/c. A 26 % compression in volume at 10.3 GPa and remarkable decreases in I-I distances between the adjacent molecules suggest a preliminary process for the metallization.