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)

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(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