Charge-transfer chemistry of chalcogen–nitrogen π-heterocycles

Recent achievements in the charge-transfer chemistry of 1,2,5-chalcogenadiazoles, 1,2,3-dichalcogenazoles (chalcogen is S, Se, or Te), their fused congeners and hybrids are discussed with special emphasis on the synthesis and structural and functional characterization of radical anions, radical-anion salts, charge-transfer complexes, neutral and charged donor–acceptor complexes, and metal coordination compounds.