NOVEL CONDUCTING COPPER-COMPLEXES DERIVED FROM THIOPHENE-FUSED DCNQIS AND COPPER(I)IODIDE

An isomeric pair of thiophene-fused dicyanoquinonediimines 1 and 2 have been prepared and reacted with copper(1) iodide to afford a novel class of highly conducting complexes of Cul, which are represented by the formulae 1(Cul)(2) and 2(Cul)(2), respectively. The temperature dependent conductivities of these complexes, as measured from compressed powder samples, exhibited metallic behaviour down to ca. 170 K, with room temperature conductivities of 45 S cm(-1) for 1(Cul)(2) and 100 S cm(1) for 2(Cul)(2). The principal structural features were deduced from EXAFS analysis; the copper ligand environment is composed of an average of three iodine atoms at 2.65 Angstrom and two nitrogen atoms at 1.95 Angstrom. The results were accounted for by a structure composed of polynuclear Cul chains bridged by bidentate ligands 1 or 2. The X-ray powder diffraction patterns of 1(Cul)(2), and 2(Cul)(2) were essentially identical to each other and suggested a highly layered structure. With regard to the electrical transport properties a hole conduction along the Cul chains was suggested by thermoelectric power and X-ray photoelectron spectroscopy measurements.