Structural and physical properties of x-(bedt-ttf)2cf3so3

Summary form only given. We have recently reported the first /spl kappa/-phase with the oxygen analog of BEDT-TTF, namely /spl kappa/-(BEDO-TTF)/sub 2/CF/sub 3/SO/sub 3/, and we have suggested that the /spl kappa/-phase salts can be classified into two groups. The group I contains the phases that undergo a superconducting (SC) phase transition at low temperature and in the group II are grouped those which undergo a progressive metal to insulator (MI) transition. The (BEDT-TTF)CF/sub 3/SO/sub 3/ system has been investigated by Chasseau et al, but the /spl kappa/-(BEDO-TTF)/sub 2/CF/sub 3/SO/sub 3/ was not reported. The d.c. conductivity measurements show a MI transition around 200 K whereas the temperature dependence of the ESR linewidth is rather characteristic of the group I giving rise to a SC ground state. The E.H.T. which allows us to calculate the /spl pi/ electronic structure of these /spl kappa/-salts takes only into account the topology of the electronic interactions between the organic molecules. The analysis shows that to differentiate between the two types of /spl kappa/-salts it is necessary to examine the electrostatic interactions between cationic and anionic layers as well as the permanent dipole existing in the non-centrosymetric counter-ions which should play a role in the localization process.