4 NEW ET-BASED AND TTM-TTF-BASED CT SALTS WITH CU-CONTAINING BINUCLEAR POLYHALIDE COMPLEX ANIONS - SYNTHESIS, PROPERTIES, AND STRUCTURE

Four new CT salts with Cu-containing binuclear polyhalide complex anio ns ET(3)Cu(2)Br(x)(x similar to 5) (A), ET(3)Cu(2)Cl(4) (B), (TTM-TTF) Cu2Br4.72 (C), and (TTM-TTF)(2) Cu2Cl6 (D) [ET=BEDT-TTF=bisethylenedi thio-tetrathiafulvalene, TTM-TTF=tetrathiomethyl-tetrathiafulvalene] a re prepared and the degree of charge transfer as well as the valence s tates of the Cu atom in the four CT salts are discussed based on the a nalysis of X-ray photoelectron spectroscopy. The conductivity of the f our charge-transfer salts A, B, C, and D at room temperature and their temperature dependence from room temperature down to 77 K along the c rystal growth direction are reported. A behaves metallic down to about 250 K, then turns to a semi-conductor; B is an organic metal down to liquid nitrogen temperature; C shows a semi-conducting behavior down t o about 230 K, then turns to an insulator and D is an insulator. The c rystal structures of C and D are determined. In crystal C, both donors and accepters occupy symmetry centers in the cell and are stacked in segregated columns. We have observed short intracolumnar and intercolu mnar S...S contacts of 3.214(10), 3.417(12)Angstrom, respectively in t he donor columns; the binuclear polybromide metal complex acceptor ani ons are planar and stacked forming complicated polymeric columns along the b axis, the Cu atom of each of the polymeric columns is five-coor dinate. In crystal D, the donor molecules TTM-TTF form dimers and the plane is almost perpendicular to that of the metal complex anion (Cu2C l6)(2-).