Synthesis, Structures, and Redox Behavior of Methyl-substituted Derivatives of Thiophene-inserted [3]Dendralene with Redox-active 1,3-Dithiol-2-ylidene Units

Several derivatives of 1,3-dithiole[3]dendralene with one thiophene spacer (1) were newly prepared. X-ray structure analysis of the hexamethyl-1 (1Aa) revealed that 1Aa adopts a structure with significant distortion between the central 1,3-dithiole (DT) ring and the thiophene ring. Cyclic voltammo-grams of all the derivatives were composed of three pairs of one-electron redox waves in correspondence with the presence of three redox-active DT rings. The results of cyclic voltam-metry and spectroelectrochemistry indicated that a positive charge in 1Aa center dot+ is mainly delocalized on the vinyl-extended tetrathiafulvalene (TTF) moiety, while two positive charges in 1Aa2+ are mainly distributed on the thiophene-inserted TTF moiety. X-ray structure analysis revealed that two-electron oxi-dation of 1Aa with (4-BrC6H4)3N center dot+SbCl61 gradually facilitat-ed the formation of a dicationic species of its chlorinated product.