Crystal and molecular structure of 7-oxabicyclo [2,2,1] hept-5-ene-2,3-exo-dicarboxylic anhydride.

Abstract

The crystal and molecular structure of the title compound (I) has been determined by three-dimensional X-ray analysis from 750 non-zero reflexions measured photographically. The compound crystallizes in the orthorhombic system, space group P212121 with a = 7-00 ± 0 02, b - 18-93 ± 0 03, and c = 5-38 ± 0-01 Á, Z = 4. The crystal structure has been solved by the symbolic addition procedure applied to non-centrosymmetnic crystals, and refined by least-squares calculations to R 0 087. The compound has the exo-conformation. The introduction of an oxygen atom in position 7 of the norbornene skeleton produces Interesting modifications in some bond distances and angles.