A study of the conformation of syn-3,7-dibromo-cis,cis-cyclo-octa-1,5-diene in the crystal and in solution by X-ray crystallography and nuclear magnetic resonance

Abstract

An X-ray structure analysis shows crystals of the title compound (II) to possess a twist-boat conformation; ¹H n.m.r., dipole moment and i.r. measurements reveal the presence of this form as the major conformer in solution. A dihedral angle interrelation table facilitates the study of this potentially mobile system.

Crystals are orthorhombic, space group Fdd2, Z= 8, a= 19·64, b= 19·36, and c= 4·78 Å. The structure was solved from photographic data by the heavy-atom method and refined by least-squares to R 0·112 for 470 independent reflections.