One-Dimensional CuBr42- Ion Array and CuBr3- Ion Chain Included in the Conducting Framework Composed of Bis(methylthio) tetrathiafulvalenothioquinone-1,3-dithiocarbonatodithiolemethide Molecules

The reaction of a new donor molecule having a planar but largely bent skeleton, bis(methylthio)tetrathiafulvalenothioquinone-1,3dithiocarbonatodithiolemethide (1), with CuBr2 in CH3CN/CS2 afforded a black-colored crystal with a formula of 14·CuBr4·2CuBr3. In the crystal 1 molecules are one-dimensionally stacked to form half-cut pipelike columns, which are arranged to construct two different shapes of channels included by a one-dimensional array of CuBr42- ions and a bibromide-bridged linear chain of CuBr3- ions with a square-pyramidal geometry at the Cu atom, {CuBr3-}n, respectively. The room-temperature electrical conductivity on the single crystal of 14·CuBr4·2CuBr3 was 2.0 × 10^-2 S cm^-1, and the temperature dependence of electrical conductivity was semiconducting with a large activation energy of 160 meV. The interactions between the neighboring Cu(II) d spins in the one-dimensional S = 1/2 spin systems due to CuBr42- ions and CuBr3- ions in {CuBr3-}n were both antiferromagnetic, and the magnitudes were moderate (Weiss temperature, v= -18 K) in the former spin system and fairly large (coupling constant, J/kB = -120 K) in the latter spin system, which was in marked contrast to a moderate and ferromagnetic {CuBr3-}n chain in the cyclohexylammonium salt already known.