Insecticides. XIII. Crystal structure of isobenzan (exo-1,exo-3,4,5,6,7,8,8-Octachloro-1,3,3a,4,7,7a-hexahydro-endo-4,7-methanoisobenzofuran)

Abstract

The crystal structure of isobenzan was determined by direct methods. The crystals are monoclinic, (C2/c) with Z = 16, in a cell of dimensions a = 2571(1), b = 1735(2), c = 1361(1) pm; β = 100.65(1)°. The structure was refined by least squares to R 0.073 with 1650 unique reflections collected on an automated equi-inclination diffractometer. The two molecules (A, B) of isobenzan in the asymmetric unit are similar and possess the exo-1,exo-3-chlorine arrangement and the endo tetrahydrofuran configuration, previously proposed on the basis of chemical evidence. This results in the molecules possessing approximate C_s(m) point symmetry with the bridgehead carbon and its attached chlorines, and the epoxide oxygen lying in the mirror plane. There is no evidence of intermolecular association involving oxygen or chlorine.