CRYSTAL-STRUCTURES AND MOLECULAR PACKING OF TETRAKIS(ALKYLTHIO)TETRATHIAFULVALENE (TTCN-TTF) .2. (N=7,9,11)

The crystal structures of tetrakis(alkylthio)tetrathiafulvalene (TTC(n)-TTF) with long alkyl chains (7 less-than-or-equal-to n less-than-or-equal-to 11) can be divided into two different groups (Form I and Form II) according to the difference in the arrangement of the alkyl chains. Although the crystals of TTC7-TTF exhibit two phases (triclinic and monoclinic), the stacking manner of these phases is nearly the same, Form II. TTC9-TTF crystallizes in two different forms: Form I (the triclinic phase) and Form II (the monoclinic phase). The TTC11-TTF crystal only adopts the Form I structure. Although the molecules in both forms have chair-like shapes and columnar structures, the alkyl chains in the Form I crystals are arranged parallel to each other, resulting in more strongly fastened packing than in the case of the Form II crystals. These results are associated with changes in the electrical resistivities and activation energies of TTC(n)-TTF over the range of large n.