Efficient synthesis of ethylenedioxotetrathiafulvalene (EDO-TTF) and analysis of the role of S center dot center dot center dot 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 th at of the corresponding acid and amide derivatives, EDO-TTF-CO2H and EDO-TT F-CONRR' (R, R' = H, Me), whose redox potentials are also reported. The X-r ay 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 othe r TTF derivatives, such as EDT-TTF. EDT-TTF-CO2H and the parent symmetrical ly substituted BEDT-TTF and BEDO-TTf, revealing that a large number of sulf ur atoms in the molecule stabilizes a face-to-face diad association through S...S van der Waals interactions with a characteristic bond-over-ring over lap while an increased number of light (C, H, O) atoms, as found in BEDO-TT F, leads to solid scare associations reminiscent of the herring-bone patter n described for the smallest polynuclear aromatic hydrocarbons. (C) 2000 Ac ademie des sciences / Editions scientifiques et medicales Elsevier SAS.