organic compounds
2-Chloro-5-p-toluylamino-N-p-tolyl-4-p-tolylamino-6-pyrimidinecarboxyamide, C27H24ClN5O2, crystallizes in two forms: orthorhombic (I) and triclinic (Ia). The orthorhombic form is almost isomorphous with the crystals of N-p-tolyl-5-benzoylamino-2-chloro-4-p-tolylamino-6-pyrimidinecarboxyamide. The triclinic form is almost isomorphous with the crystals of N-p-tolyl-2-chloro-5-p-toluylamino-4-p-tolylamino-6-pyrimidinecarboxyamide, C26H21Cl2N5O2 (II). The molecules of I, Ia and II are almost planar but are slightly bowed: the near-planarity is due to the intramolecular hydrogen bonds which are almost identical in all these structures, with N-H amide groups participating in intramolecular hydrogen bonds as donors, while each carbonyl O atom and one pyrimidine N atom are acceptors. In crystals of I the molecules are arranged in polymeric chains running along the a axis. In crystals of Ia and II the molecules are arranged in dimers linked across crystallographic inversion centres by weak intermolecular hydrogen bonds.