Synthesis, Reactions, and Selected Physico-Chemical Properties of 1,3- and 1,2-Tetrachalcogenafulvalenes

This review describes the synthesis of 1,3- and 1,2-tetrachalcogenafulvalenes, the chemical transformation of substituents, reactions of the ring systems and the synthesis of polymers with 1,3-tetrathiafulvalene units in the backbone and in the side chain. For selected charge-transfer complexes of tetrachalcogenafulvalenes the relation between molecular structure and solid-state structure, respectively, and electric conductivity are discussed. Superconducting properties of some charge-transfer complexes with tetrachalcogenafulvalenes as donor are reported. Preparations of important starting compounds for the synthesis of tetrachalcogenafulvalenes (like 1,2- and 1,3-dithiole, 1,3-thiaselenole, and 1,3-diselenole derivatives) have been considered in this review. Selected properties (melting point, UV-VIS absorption data and oxidation potentials) of 1,2- and 1,3-tetrachalcogenafulvalenes are summarized in appropriate tables.