New organic superconductors consisting of an unprecedented pi-electron donor.

The synthesis and electrochemical properties of a new organic donor, (1,4-dioxan-2,3-diyldithio)dihydrotetrathiafulvalene (DODHT), and the crystal structures and physical properties of its superconducting salts are described. The DODHT molecule has the bulky dioxane ring condensed by cis fusion, and the reduced pi-electron system of DODHT, as compared with conventional tetrachalcogenafulvalene donors, leads to both the weak electron-donating ability and the large on-site Coulomb energy. Nevertheless, DODHT produces the superconducting AsF6 and PF6 salts, which are isostructural and exhibit superconducting transitions at 3.3 and 3.1 K, respectively, under 16.5 kbar.