Developments of peri-dichalcogen-bridged fused aromatic hydrocarbons as novel electron donors forming conductive molecular complexes

The developments of novel non-TTF type electron donors forming conductive molecular complexes are presented, especially focussing on methyl-substituted tetrachalcogeno-naphthalenes, anthracenes, and tetracenes. These compounds have been designed chiefly to possess advantageous characteristics, such as strong donating ability, enhanced solubility, and marked heteroatomic interaction, all of which are essential to electron donors forming organic metals. As a result, they formed a large number of conductive molecular complexes and radical cation salts. In particular, the NO₃^-, BF₄^-, and Cl^- salts of the dimethyl tetraselenoanthracene showed high room temperature conductivities of 440, 450, and 700 Scm^-1, respectively, with metallic behavior. Furthermore, the Br^- salt of the dimethyl tetratelluroanthracene showed an extraordinarily high conductivity of 1300 Scm^-1.