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

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 = 2 516.1 (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 conformational angles like those of DDE