Efficient synthesis of ethylenedioxotetrathiafulvalene (EDO-TTF) and analysis of the role of S•••S van der Waals interactions in the crystal chemistry of neutral TTF derivatives

An efficient synthesis of ethylenedioxotetrathiafulvalene (EDO-TTF), a non-symmetrically substituted tetrathiafulvalene, is described together with that of the corresponding acid and amide derivatives, EDO-TTF-CO2H and EDO-TTF-CONRR' (R, R' = H, Me), whose redox potentials are also reported. The X-ray crystal structures of EDO-TTF and EDO-TTF-CO2H have been determined and the solid state arrangement of the two compounds compared with that of other TTF derivatives, such as EDT-TTF. EDT-TTF-CO2H and the parent symmetrically substituted BEDT-TTF and BEDO-TTf, revealing that a large number of sulfur atoms in the molecule stabilizes a face-to-face diad association through S...S van der Waals interactions with a characteristic bond-over-ring overlap while an increased number of light (C, H, O) atoms, as found in BEDO-TTF, leads to solid scare associations reminiscent of the herring-bone pattern described for the smallest polynuclear aromatic hydrocarbons. (C) 2000 Academie des sciences / Editions scientifiques et medicales Elsevier SAS.