Benzo-fused dithiazolyl radicals: from chemical curiosities to materials chemistry

Synthetic routes to benzo-fused 1,2,3- and 1,3,2-dithiazolylium salts are described. Their chemical stabilities and physical properties, especially their redox behaviour, are discussed. One electron reduction yields the corresponding benzo fused 1,2,3- and 1,3,2-dithiazolyl radicals. The electronic properties of the dithiazolyl ring are compared with a series of isoelectronic sulphur–nitrogen rings including dithiadiazolyl and trithiadiazolylium radicals. The ability to tune the redox behaviour of the dithiazolyl ring by changing the substituents, coupled with the lower dimerisation energy afforded by delocalisation of the unpaired electron makes these molecules attractive building blocks for the construction of molecular conductors and magnets. Recent results in this area are summarised.