Commensurate Urea Inclusion Crystals with the Guest (E,E)-1,4-Diiodo-1,3-Butadiene

The urea inclusion compound (UIC) with (E,E)-1,4-diiodo-1,3-butadiene (DIBD) as a guest (DIBD:UIC) has been prepared and crystallographically characterized at 90 and 298 K as a rare example of a commensurate, fully ordered UIC. The crystal shows nearly hexagonal channels in the monoclinic space group P21/n. The DIBD guest molecules are arranged end-to-end with the nonbonding iodine atoms in van der Waals contact. The guest structure is compared with that for DIBD at 90 K and with computations for the periodic UIC and isolated DIBD molecule.