X-Ray crystal structures of two pyrethroid insecticides: cis-3-phenoxybenzyl 3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate and the 3-(2,2-dichlorovinyl) analogue

Abstract

The crystal structurs of two isomorphous crystalline pyrethroid insecticides have been determined by X-ray diffraction analysis. Both compounds crystallise in the orthorhombic space group P2₁2₁2₁ with Z= 4. The bromo-compound (I) has cell dimensions a= 12.177(4), b= 26.707(9), and c= 6.146(5)Å. The structure was solved by heavy-atom methods from diffractometer intensity data, and refined to R 0.044 for 721 observed reflections. The absolute configuration was determined and confirmed the chemical work. The chloro-compound (II) has cell dimensions a= 12.168(16), b= 26.577(22), and c= 6.006(4)Å. Intensity data were collected from films scanned on a microdensitometer, and the structure refined to R 0.069 for 545 observed reflections.

The conformations of the two compounds are compared with each other and with those of other known pyrethroid structures in the crystalline state.