THE CRYSTAL PACKING MODES OF 3 STERICALLY OVERCROWDED IMIDAZOLE DERIVATIVES

The crystal packing of racemic lamino-5-hydroxy-1,5-diphenyl-Delta(3)- imidazolin- 2-one resembles the bilayered packing arrangements with al ternating hydrophilic and hydrophobic layers observed in the crystal s tructures of lipids. The hydrophobic layers of the imidazolinone are b uilt up individually by phenyl and cyclohexyl groups. In contrast, the corresponding 4-tert-butylamino derivative crystallizes optically res olved in a non-bilayer layer structure. This crystal packing is simila r to the host-lattice of the inclusion compound formed by 9-(4-tert-bu tylphenyl)fluoren-9-ol and dioxane [Csoregh, Weber, Nassimbeni, Gallar do, Dorpinghaus, Ertan & Bourne (1993). J. Chem. Sec. Perkin Trans. 2, pp. 1775-1781]. The major building units of 4-tert-butylamino-1,5-dip henylimidazole are centrosymmetrical dimers in which the molecules dis play a 'yin-and-yang'-like self-complementarity. The dimers pack in co lumns, which form a distorted hexagonal pattern.