Electronic Interactions in a New π‐Extended Tetrathiafulvalene Dimer

The first it-extended tetrathiafulvalene (exTTF) dimer in which the two exTTF units are covalently connected by 1,3-dithiole rings has been obtained in a multistep synthetic procedure involving the Ullmann cross-coupling reaction by using copper(i) thiophene-2-carboxylate (CuTC). The electronic spectrum reveals a significant electronic interaction between the exTTF units. The electrochemical study carried out by cyclic voltammetry in solution and in thin-layer conditions, and the electrochemical simulation and spectroelectrochemical (SEC) measurements confirm the electronic communication and show that the oxidation of dimer 14 occurs as two consecutive 2e - processes D 0 -D 0 →D 2+ -D 0 →D 2+ -D 2+ . Theoretical calculations, performed at the B3P86/6-31G* level, confirm the experimental findings and predict that 14 2+ exists as a delocalized D ·+ -D ·+ species in the gas phase and as a localized D 2+ -D 0 species in solution (CH 3 CN or CH 2 Cl 2 ). Oxidation of 14 2+ forms the tetracation 14 4+ which is constituted by two aromatic anthracene units bearing four aromatic, almost orthogonal 1,3-dithiolium cations.