Synthesis, Electrochemistry, and Crystal Structure of N,N′-Dicyanoquinonediimine (DCNQI) Derivatives Containing Fused Benzene Rings

A series of novel fused aromatic N,N′-dicyanoquinonediimines (DCNQI) derivatives (3, 5, 7, and 9) and N-cyanoquinonemonoimines (4, 6, 8, and 10) has been synthesized by reaction of the corresponding quinones with bis(trimethylsilyl)carbodiimide (BTC). The acceptor ability is discussed in terms of both steric and electronic effects. Cyclic voltammetric data reveal two one-electron reduction waves of the corresponding radical-anion and dianion of each compound. The first reduction potentials are more negative than those of the more simple DCNQI (2a) and TMDCNQI (2b) acceptors. In contrast, the novel hybrid acceptor molecule 13 shows a single two-electron wave which corresponds to the dianion. The X-ray analysis of acceptor 13 allows one to compare, for the first time, the structural effect of the dicyanomethylene and N-cyanimine groups on the same molecule.