Crystal and electronic structure of (BEDT-TTF)2Br·CH2(OH)CH2OH and (EDT-TTF)3(Hsq)(H2sq) (H2sq = squaric acid)

In a 2a × b × c superstructure phase of (BEDT-TTF)2Br·CH2(OH)CH2OH, intermolecular hydrogen bonds are disordered, whereas the conformational change of donors six-membered rings from the metallic phase is observed. The Seebeck coefficient around the room temperature is proportional to the temperature, which is characteristic to the conventional metallic state. The crystal structure of (EDT-TTF)3(Hsq)(H2sq) is characterized as the presence of one-dimensional donor columns bridged with strongly hydrogen-bonded anion ribbons. This salt shows a semiconductive behavior, whose origin is described in terms of either Mott or Peierls states.