Synthesis, Structures, and Redox Behavior of Furan‐Inserted [3]‐and [5]Dendralene Derivatives With Redox‐Active 1,3‐Dithiol‐2‐ylidene Units

ABSTRACT Derivatives of furan‐bridged 1,3‐dithiole[3]dendralene ( 2 ) and 1,3‐dithiole[5]dendralene ( 3 ) analogs were synthesized. X‐ray analysis of the bis(ethylenedioxy)‐bis(methylthio)‐ 2 ( 2Cee′ ) revealed a slightly distorted geometry between the central 1,3‐dithiol‐2‐ylidene (DT) moiety and the furan spacer. Cyclic voltammetry exhibited three reversible redox pairs for 2 and five for 3 , in correspondence with the number of DT‐rings. Spectroelectrochemical measurements and X‐ray analysis indicated that the positive charges in the oxidized states of 2 are delocalized over the three DT units. In contrast, the oxidized species of 3 appear to exist in equilibrium between two conformations: One with charge localized on the 2 moiety and the other on the vinyl‐extended tetrathiafulvalene (TTF) fragment. In the dicationic state of 3 , one positive charge resides on each moiety of 2 and vinyl‐extended TTF.