The crystal chemistry and torsional profiles of three polymorphic diarylami
nes have been compared and contrasted. Although they have similar potential
energy surfaces (PESs) for the main rotatable bond, the torsional distribu
tion of the observed polymorphs differs greatly. In particular there are re
ported crystal structures for some but not all of the molecules at various
positions on the PES, some of which are either maxima or non-stationary poi
nts on the gas phase surface. We have explained the distribution of the obs
erved torsion values and postulated new packing motifs based on those found
in the other molecules. According to lattice energy calculations, some of
these 'new polymorphs' are predicted to be more stable than those reported
in the literature.