Organic Conductors Based on Multi-Sulfur π-Donor And/Or π-Acceptor Molecules-Bedt-Ttf, Bmdt-Ttf, Bpdt-Ttf, And m(dmit)2-

Crystal and electronic structures of various types of molecular metals based on multi-sulfur π-donor and π-acceptor molecules are presented. Band structures of (BEDT-TTF)2 C104 (TCE)0.5 and (BEDT-TTF)3 (C104)2 indicate their semimetallic (or narrow-gap semiconductive) properties. In β-(BEDT-TTF)2 PF6, BEDT-TTF dimers are arranged along the transverse direction and the Fermi surface is open perpendicular to this direction. The superconducting β- (BEDT-TTF)2 I3 has nearly isotropic 2-D Fermi surface. The positive charges in (BMDT-TTF)3 C104 (DCE) tend to localize and form a Wigner lattice. Similar charge separation makes (BMDT-TTF)3 FF6 (DCE) a 1-D conductor. (BMDT-TTF) (TCNQ), (DBTTF) [Ni(dmit)2], and (TMTSF) [Ni (dmit)2] are twochain compounds with high conductivities ([sgrave]R.T = 200-300 Scm−1). (BMDT-TTF) (TCNQ) has crossing bands, whereas the others have parallel bands. (TMTSF)-[Ni(dmit)2] has a periodically modulated superlattice (a, 9b, c).