Chalcogen–Nitrogen Heterocyclic Radicals

Recent progress in organic spin science associated with neutral 1,2,3- and 1,3,2-benzodichalcogenazolyls (Herz and Wolmershäuser radicals, respectively), and anionic 2,1,3-benzochalcogenadiazolidyls and 1,2,3-benzodichalcogenazolidyls, involved in the design and synthesis of molecular conductive and magnetic materials, including spin-crossover materials, is discussed. Where reasonable, the monocyclic analogues and other relevant ring systems are covered. Typically, S incarnations are better studied than Se and, especially, Te ones. Meanwhile, the latter are of enhanced interest due to stronger spin–orbit coupling, higher polarizability, and a larger propensity to secondary soft–soft bonding interactions. Their synthesis and characterization are challenging for further research.