4-iodonitrobenzene and 4-iodocyanobenze show similar
crystal packing. Geometrical factors are important in the
crystal packing. Shape of a molecule in a crystal is related
to the repulsive potential field around.
But as seen in 3-Iodonitrobenzene, recognition motifs
depend on the substitution pattern on the benzene ring.
Crystal Growth & Design 6 (2006)