STRUCTURES OF LOW-DIMENSIONAL ORGANIC CONDUCTORS OF THE (BET-TTF) ReO4 FAMILY

L. V. Zorina1, S.S. Khasanov1, B.Zh. Naryrnbetov1, L.P. Rozenberg1, R.P. Shibaeva1, A. Perez2, J. Veciana2, C. Rovira2, V.N. Laukhin3, E. Canadell2

1Institute of Solid State Physics RAS, Chernogolovka, MD, 142432 Russia
2Instiut de Ciencia de Materals de Barcelona (CSIC)
3Institute of Chemical Physics RAS, Chernogolovka, MD, 142432 Russia

The p-electron donor bis(ethylenethio)tetrathiafulvalene (BET-TTF)

forms a large variety of charge-transfer salts with different anions. Some of them exhibit metallic properties. We have studied three radical cation salts of the (BET-TTF) - ReO4 family. The crystal and electronic band structures at room temperature as well as the conducting properties will be presented and discussed. The main crystal data of the triclinic single crystals (space group P1_) are following:

  1. (BET-TTF)·ReO4: a=7.760(8), b=8.890(5), c=12.325(4)A, a=73.95(4), b=113.47(5), g=87.31(6)°,. V=737.6 A3, Z=2.
  2. (BET-TTF)3(ReO4)2: a=6.370(2), b=7.788(4), c=22.865(5)A, a=84.60(3), ß=89.50(2), g=70.25(3)°, V=1062.5 A3, Z=1.
  3. (BET-TTF)9(ReO4)4.2H2O: a=11.015(6), b=19.324(5), c=17.749(4)A, a=120.94(2), b=89.75(3),g=91.87(3)°, V=3238.3A3, Z=l.

The 3:2 and 9:4 radical cation salts are metallic down to 125 and 75 K, respectively, with a transition to the semicunducting state, while the 1:1 salt has a semiconductor behavior. These three phases are clearly differentiated by their EPR and optical spectra.

Figure: Structure of (BET-TTF)3(ReO4)2