MOLECULAR AND CRYSTAL-STRUCTURE AND POLYMORPHISM OF HYL-5-PHENYL-2H-PYRAZOLO[1,5-C]BENZ[E]-1,3-OXAZINE

The X-ray crystal structure of hyl-5-phenyl-2H-pyrazolo[1,5-c]benz[e]- 1,3-oxazine was determined. In the crystal phase, this compound forms two polymorphic modifications: a monoclinic form (a = 19.420, b = 10.9 29, and c = 9.180 Angstrom; beta = 95.29 degrees; sp. gr. P2(1)/c; Z = 4' and R = 0.077 for 1147 reflections) and an orthorhombic form (a = 20.615, b = 62.252, and c = 6.040 Angstrom; sp. gr. Fdd2; z = 16; and R = 0.063 for 614 reflections). Both forms have equal lattice energies . The examination of the molecular packings in the crystals revealed t hat the transition between the two polymorphic modifications requires crystal damage. Effects of annelation by the benzene and pyrazoline ri ngs on the confirmation of the oxazine ring were studied.