First-order phase transition in the organic metal kappa-(BETS)(2)C(CN)(3)

Evidence concerning the occurrence of a first-order phase transition around 260 K in the organic metal kappa-(BETS)(2)C(CN)(3) is reported and the eff ect of the transition on the crystal and electronic structure of the salt i s discussed. Determination of the crystal structure at 50 K has shown that the main structural change brought about by the transition affects the anio n sublattice. Although there are noticeable changes in the chalcogen . . . chalcogen short contacts of the donor lattice it is shown that the Fermi su rface is left unaltered by both the first-order transition and the thermal contraction down to 50 K.