Insecticides. Part 8. Crystal structures of 1,1-bis-(p-chlorophenyl)acetic acid (DDA) and 4,4′-dichlorobenzophenone (DBP)

Abstract

The crystal structure of DDA has been determined by direct methods from three-dimensional diffractometer data. Z= 4 in the monoclinic unit cell, space group P2₁/c, a= 1 411.3(2), b= 612.3(1), c= 1 600.5(2) pm, β= 111.51(1)°. The structure was refined by least squares to R 0.079 for 1 600 observed reflections. DDA is nonactive but has conformational angles similar to those of DDT. It forms a dimer, with its centre at a centre of symmetry, and a hydrogen bond of 200 pm. The structure of 4,4′-dichlorobenzophenone (DBP) was determined by the same methods. Z= 4 in the monoclinic cell, space group C2/c, a= 2 5161 (11), b= 612.8(3), c= 758.6(3) pm, β= 102.05(3)°. The molecule has a space-group implied two-fold axis. It is non-active and has small conform ational angles like those of DDE.