On the aromaticity of tetrathiafulvalene cations

The gain of aromaticity upon oxidation of tetrathiafulvalene (TTF) is investigated based on magnetic and energetic criteria. Thus, Nucleus Independent Chemical Shift (NICS) indices are calculated for a selection of TTF derivatives, including the protonated TTF, and compared to proton chemical shifts measured experimentally. The aromatic stabilization energy of the TTF dication, represented by the isomerization stabilization energy, is also calculated and compared to that of 1,3-dithiolium. (C) 2008 Elsevier B.V. All rights reserved.