Electrical conductivity and DFT investigations of a 2D Cu^I-TCNQ^II- framework

An investigation of the coordination polymer, [Cu-2(Me(2)pz)(TCNQ)] (Me(2)pz = 2,5-dimethylpyrazine) is described. The structure of [Cu-2(Me(2)pz)(TCNQ)] is comprised of 2D sheets with mean plane sheet-to-sheet separations closer than that of graphene sheets in graphite. Electrical conducticity measurements on the framework indicate semiconductor behaviour with a sigma(300K) = 9.8 x 10(-8) S cm(-1) and an E-a = 0.43(3) eV. Density functional theory studies reveal a band structure comprised predominatly by donor TCNQ and acceptor Me(2)pz ligand-p oribtals. This investigation also resulted in the formation of Cu(TCNQ) (phase I) from the reaction mixture that yielded [Cu-2(TCNQ)(Me(2)pz)]. A redetermination of the crystal structure of Cu(TCNQ) is reported.