Crystal Structures of Highly Conducting Iodine Complexes of TTM-TTP

Methylthio substituted bis-fused tetrathiafulvalene, TTM-TTP (2,5-bis[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-1,3,4,6-tetrathiaphentalene) makes three phases of iodine complexes: (TTM-TTP)I3, α-(TTM-TTP)2I3, and β-(TTM-TTP)2I3. The 1 : 1 complex exhibits high conductivity, 700 S cm−1 at room temperature, and is metallic down to about TMI = 160 K. This complex has uniform columns of the donor molecules. In the semiconducting α-(TTM-TTP)2I3, one quarter of the donors is incorporated in the anion sheet, and the sides of the other trimeric donors are blocked by the anion sheets. β-(TTM-TTP)2I3 shows metallic conductivity down to TMI = 20 K.