Synthesis of novel chloro-substituted N, N′-dicyanoquinonediimines. Formation of charge transfer complexes and copper radical-anion salts

Abstract

Novel chloro-substituted N, N′-dicyanoquinonediimines (DCNQIs) ( 5) have been synthesized from the corresponding quinones ( 4) by reaction with bis(trimethylsilyl)carbodiimide (BTC) and titanium tetrachloride. Cyclic voltammetry (CV) measurements of the prepared DCNQIs ( 5) exhibited the presence of two one-electron reversible reduction waves to the corresponding radical anion and dianion. The first reduction potential revealed a better acceptor ability of compounds 5 than the parent DCNQI, these values being strongly dependent on the presence of chlorine atoms. The 1H NMR high resolution spectral data showed, when possible, the presence of the syn-anti isomers in these compounds ( 5). Charge transfer complexes ( 6) of the novel DCNQIs ( 5) with the donor tetrathiafulvalene (TTF) and also the copper radical-anion salts ( 7) have been obtained. Room temperature conductivities of the charge transfer complexes ( 6) and charge transfer salts ( 7) were measured and the temperature dependence exhibited a semiconducting behaviour.