2,1,3-Benzothiadiazole Dimers: Preparation, Structure, and Transannular Electronic Interactions of syn- and anti-[2.2](4,7)Benzothiadiazolophanes

The cyclophanes comprised of two 2,1,3-benzothiadiazole (BTD) rings, anti- and syn-[2.2](4,7)benzothiadiazolophanes (anti-1 and syn-1), were prepared for the first time. The differences of the physical properties in the overlapping mode of the pi-systems are clearly observed, and syn-1 shows much more significant transannular pi-electronic interactions than anti-1 especially in the redox properties and the stability of the radical anion species.