Crystal structures and conductivities of new hydrogen-bonded system: CnDT-EDO-TTF and BzDT-EDO-TTF

A new series of RDT-EDO-TTF [R = C5, C6, C7, C8; (cis-l,2-cycloalkylene-l,2-dithio)ethylenedioxytetrathiafulvalene and R = Bz; (benzodithio)ethylenedioxytetrathiafulvalene] donors containing cycloalkylene or benzene, and ethylenedioxy groups as a source of the steric hindrance and the intermolecular hydrogen bonds has been synthesized. The charge transfer (CT) salts, β″-(RDT-EDO-TTF)2(PF6)x (R = C5, C6, C7, C8, and Bz), have the similar β″-type donor arrangement due to the intermolecular hydrogen-bonded network (CH…O) in the two-dimensional (2D) plane. The C6DT-EDO-TTF molecule containing the flexible cyclohexylene group affords the 2:1 salts, which shows the metallic behaviors down to 1.3 K with a variety of resistivities at room temperature, 3.0 × 10−3∼5.0 × 10−2 ohm cm. On the other hand, the BzDT-EDO-TTF donor with the fixed functional benzo group gives the non-stoichiometry complexes, which exhibit the similar metallic behavior down to 1.3 K with the largest RRR = 40∼115 among the RDT-EDO-TTF salts.