Highly-conducting neutral copper complexes substituted with two tetrathiafulvalenyldithiolato groups

Abstract

The neutral bis(dialkylthiotetrathiafulvalenyldithiolato)copper complexes, Cu(R₂C₆S₈)₂ (R=Me 1a, Et 1b, R₂=–CH₂CH₂– 1c) were synthesized by the reaction of bis(tetramethylammonium or tetraethylammonium) bis(dialkylthiotetrathiafulvalenyldithiolato)zincate complexes with CuCl₂ in DMF, followed by oxidation with iodine. The room-temperature electrical conductivities were 7.8×10^–2 , 5.0×10^–4 and 3.7 S cm^–1 for compressed pellets of 1a, 1b and 1c, respectively. Magnetic susceptibility measurements showed that the remaining spin on the copper atoms is very small for these complexes as a result of large intramolecular electron transfer from Cu^II atom to the tetrathiafulvalenyl radical cation ligands.