CRYSTAL AND ELECTRONIC-STRUCTURES OF (BEDT-TTF)2(KHG(SCN)4), (BEDT-TTF)2(NH4HG(SCN)4)

The crystal structures of (BEDT-TTF)2[MHg(SCN)4] (M=K at 298 and 104 K and M=NH4 at 298 K) were determined by X-ray analyses. A donor layer and an anion sheet stack alternately along the B-axis. The packing pattern of the donor is close to α-phase, while an anion sheet constructs a thick two-dimensional polymer plane parallel to (010). The linkage of ..SC..K (or NH4) ••NCSHg-SCN in an anion sheet is very unique. The band structure calculation indicates both a closed and an open Fermi surfaces, resembling that of K-(BEDT-TTF)2[Cu(NCS)2]. © 1990 The Chemical Society of Japan.