Orthorhombic and Triclinic Forms of 2-Chloro-5-p-toluoylamino-N-p-tolyl-4-p-tolylamino-6-pyrimidinecarboxamide and 2-Chloro-5-(p-chlorobenzoylamino)-N-p-tolyl-4-p-tolylamino-6-pyrimidinecarboxamide

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.

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