Elsevier, Tetrahedron Letters, 48(54), p. 6635-6639
DOI: 10.1016/j.tetlet.2013.09.131
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Pyrazinedicyanoethylthiotetrathiafulvalene, (pzdc-TTF) (1a), an extended TTF fused with a pyrazine moiety and also a dithiolene ligand precursor, was synthesized through a cross-coupling with triethyl phosphite between pyrazine-1,3-dithiole-2-thione (I) and 4,5-bis(2-cyanoethylthio)-1,3-dithiole-2-one (III). This reaction also yields to dipyrazine TTF derivative (1b) and 2,3,6,7-Tetrakis(2-cyanoethylthio)TTF (1c), resulting from the self-coupling reactions of the thione (I) and ketone (III). The crystal structure of 1a is composed by pairs of head to head donor stacks of pzdc-TTF molecules along b in opposite orientations. Single crystals of 1b revealed a new polymorph with a face-to-face π-stacking motif. The electrochemical properties of 1a studied by cyclic voltammetry (CV) in DMF, shows two single electron oxidation processes typical of TTF-based donors; one pair of asymmetric redox waves centered at 627 mV versus Ag/Ag+ is ascribed to the couple [pzdc-TTF]+/[pzdc-TTF]2+, and one pair of quasi-reversible redox waves centered at 430 mV is ascribed to the couple [pzdc-TTF]0/[pzdc-TTF]+.