Halogen bonding, hydrogen bonding and fluorine segregation in conducting salts of novel halogenated tetrathiafulvalenes
Résumé
Two different intermolecular interactions are described and analyzed in cation radical salts of functionalized tetrathiafulvalenes. On the one hand, the electrostatic nature of the CNHal interaction is demonstrated through the observed structural modifications, (i) when halogenated TTFs such as I-EDT-TTF and I2-EDT-TTF are engaged with cyano anions where a strengthening of the interaction is noted, or (ii) when EDT-TTF-CN is engaged with halogenated anions where the CNHal interaction is totally suppressed. On the other hand, we took advantage of the absence of interactions experienced by aliphatic fluorinated molecules to investigate the structural and electronic properties of fluorinated tetrathiafulvalenes such as the bis(difluoropropylenedithio)tetrathiafulvalene. Its synthesis, electrochemical and structural properties will be described as well as different salts with linear (ICl2−) and complex (Mo6Cl142−) anions. Fluorine–fluorine segregation effects combined with C–HHal hydrogen bonds lead to striking layered structures with fluorinated bilayers while an organic–inorganic segregation is also retained with the conducting 4:1 salt of the unsymmetrically substituted (difluoropropylenedithio)tetrathiafulvalene with Mo6Cl142−.