Synthesis and redox behaviour of highly conjugated bis(benzo-1,3-dithiole) and bis(benzothiazole) systems containing aromatic linking groups: model systems for organic metals

The synthesis and electrochemical redox properties of a series of symmetrical, highly conjugated bis(benzo-1,3-dithiole) and bis(benzothiazole) derivatives (8)–(24) are described. The heterocyclic end-groups are linked by a conjugated framework that incorporates the following groups: (a) phenyl, (b) naphthyl, (c) thienyl, (d) biphenyl, (e) anthracenyl, and (f) benzanthracenyl. Compounds (13) and (16)–(19) display two, single-electron redox waves in the cyclic voltammogram, while compounds (8)–(12), (14), (15), (20), (21), (23), and (24) display a single, two-electron redox wave. The redox potentials of these molecules can be correlated with the increased stability of the redox state of the system in which the central, bridging ring is aromatic.