FACTORS AFFECTING THE METALLIC VERSUS SEMICONDUCTING PROPERTIES OF CHARGE-TRANSFER SALTS CONTAINING [M(DDDT)(2)](2) AND [M(DMIT)(2)](2) (M=PD, PT) DIMERS

To understand the structural and electronic factors controlling the metallic versus semiconducting properties of the beta-type charge transfer salts containing the [M(dddt)(2)](+)(2) and [M(dmit)(2)](-)(2) (M = Pd, Pt) dimer units, we calculated their tight-binding electronic band structures. Our analysis shows that the partially filled band of both types of salts is derived either from the HOMO or from the LUMO of their monomer unit depending upon the extent of dimerization. A good electrical conductivity is expected for strongly dimerized M(dmit)(2) systems and for weakly dimerized M(dddt)(2) systems.