Crystal and molecular structure of 3,3′-spirobi(bicyclo[3,1,0]hexane)-2,2′-dione

Abstract

Crystals of the title compound are orthorhombic with a= 25·899(4), b= 11·877(2), c= 5·885(5)Å space group Fdd2, with Z= 8 and molecular symmetry C₂-2. Intensity measurements by visual estimation from Weissenberg photographs were of limited accuracy because of inherent crystal distortion and consequently very accurate molecular dimensions could not be obtained. However the results of a three-dimensional structure analysis (R ca. 16% for 326 reflections) show unequivocally that the molecules in the crystal have the same configuration as that proposed for molecules in solution on the basis of n.m.r. measurements (S. Bien and D. Ovadia, J. Org. Chem., 1970, 35, 1028). The cyclopentanone rings are in the envelope conformation. The molecules in the crystal are in stacks extending along the c axis, the stacks being pseudo-hexagonally arranged.