Unprecedented Binary Semiconductors Based on TCNQ: Single-Crystal X-ray Studies and Physical Properties of Cu(TCNQX2) X=Cl, Br

Single crystals of a new structure type for the M+(TCNQ)•− binary family are isolated from reactions of dihalogenated TCNQ derivatives and CuI ions (see figure; Cu: pink C: black, N: blue, Br: orange, H: light blue). The new compound Cu(TCNQCl2) exhibits the highest conductivity of the M+(TCNQ)•− series to date, despite the larger separation of TCNQCl2 units in the stacks. Conductive properties of Cu(TCNQX2) where X = Cl, Br is attributed to charge‐carrier transport through copper ions, which is unprecedented in M+(TCNQ)•− materials.