ORTHORHOMBIC AND TRICLINIC FORMS OF -N-P-TOLYL-4-P-TOLYL-AMINO-6-PYRIMIDINECARBOXAMIDE AND )-N-P-TOLYL-4-P-TOLYLAMINO-6-PYRIMIDINECARBOXAMIDE

2-Chloro-5-p -N-p-tolyl-4-p-tolylamino-6-pyrimidinecarboxamide, C27H24 ClN5O2, 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-pyrimidinecarboxyamid e. The triclinic form is almost isomorphous with the crystals of 2-chl oro-5-(p- chlorobenzoylamino)-N-p-tolyl-4 -p-tolylamino-6-pyrimidineca rboxamide, C26H21Cl2N5O2 (II). The molecules of (I), (Ia) and (II) are almost planar but are slightly bowed: the near-planarity is due to th e intramolecular hydrogen bonds which are almost identical in all thes e structures, with N-H amide groups participating ire intramolecular h ydrogen bonds as donors, while each carbonyl O atom and one pyrimidine N atom are accepters, In crystals of (I) the molecules are arranged i n polymeric chains running along the a axis. In crystals of (Ia) and ( II) the molecules are arranged in dimers Linked across crystallographi c inversion centres by weak intermolecular hydrogen bonds.