Comparison of the crystal and electronic structures of three 2:1 salts of the organic donor molecule BEDT-TTF with pentafluorothiomethylsulfonate anions SF{sub 5}CH{sub 2}SO{sub 3}{sup {minus}}, SF{sub 5}CHFSO{sub 3}{sup {minus}}, and SF{sub 5}CF{sub 2}SO{sub 3}{sup {minus}}

Salts of the donor molecule, bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET), with pentafluorothiomethylsulfonate (SF{sub 5}CX{sub 2}SO{sub 3}{sup {minus}}, X = H or F) anions have been prepared. Three phases, {beta}{double_prime}-(ET){sub 2}SF{sub 5}CH{sub 2}SO{sub 3}{beta}{prime}-(ET){sub 2}SF{sub 5}CF{sub 2}SO{sub 3} and {beta}{double_prime}-(ET){sub 2}SF{sub 5}CHFSO{sub 3} (A,B, and C respectively) were obtained by electrocrystallization with the corresponding LiSF{sub 5}CX{sub 2}SO{sub 3} electrolytes. The structures of these salts were determined by single-crystal X-ray diffraction, and their physical properties were examined by electrical resistivity measurements as well as by ESR and Raman spectroscopy. The A,C and B salts are considerably different in their crystal structures, physical properties, and electronic structures despite the similarity in the structures of SF{sub 5}CX{sub 2}SO{sub 3}{sup {minus}}(X = H,F) anions. The A salt has two kinds of ET donor molecules with considerably different charge densities. The electronic structure of C has both one-dimensional (1D) and two-dimensional (2D) Fermi surfaces which are similar to those found in the organic superconductor A. The ESR data for the B salt indicate that it opens a spin gap below 45 K. The differences in the physical properties of the three salts were analyzed by calculating the HOMO-HOMO interaction energies between nearest-neighbor ET molecules in their donor molecule layers.