Synthesis, structure, and electronic properties of (BEDT-TTF)(R1R2TCNQ); (R1=R2=H,F,Cl,Br,CH3)

Charge transfer complexes of BEDT-TTF with various TCNQ derivatives are synthesized. Mono-halogenated TCNQ afforded highly conductive complexes. A variety of structures was found for 2,5-di-substituted TCNQ: Me2- and ClMe-TCNQ yielded mixed-stack complexes, while BrMe-, Br2-, and Cl2-TCNQ gave segregated-stack complexes, being metallic or semiconductive. The correlation between the structure of the acceptor and that of the resultant CT complex is also discussed.