Triselenathiafulvalenes: A novel sulphur-selenium interchange on trimethyl phosphite coupling of substituted 1,3-diselenole-2-thiones

Coupling using trimethyl phosphite of 4,5-dimethoxycarbonyl- and 4,5-ditrifluoromethyl-1,3-diselenole-2-thiones unexpectedly gave only tetramethoxycarbonyl- and tetratrifluoromethyl-triselenathiafulvalene respectively, while self-coupling of 4,5-dimethyl-1,3-diselenole-2-thione provided a mixture (85:15) of tetramethyltetraselenafulvalene and tetramethyltriselenathiafulvalene.