UV irradiation of hitherto unknown 4, 5-bis-benzo [b] thiophen-3-yl-[1, 3] dithiol-2-one gave 3- (3-benzo [b] thienyl)-thieno [3, 4-c] benzo [e][1, 2] dithiine by loss of carbon monoxide and rearrangement, whereas 4, 5-bis-(2-bromo-phenyl)-[1, 3] dithiol-2-one gave a polymeric material containing S–S bridges. The structures of both photoproducts were demonstrated on the basis of chemical behaviour and/or X-ray diffraction.
