Structures of four polymorphs of the pesticide dithianon solved from X-ray powder diffraction data

The crystal structures of four polymorphs of the pesticide dithianon (5,10-dihydro-5,10-dioxonaphtho[2,3-b]-1,4-dithiine-2,3-dicarbonitrile) have been solved from powder diffraction data and refined using the Rietveld method. Three polymorphs crystallize in non-centrosymmetric space groups. Two polymorphs have Z' > 1. The structures are assembled via interactions between carbonyl groups of quinoid fragments into layers which further interact only by weak interactions.