NOVEL PI-EXTENDED THIOPHENE-FUSED ELECTRON-ACCEPTORS FOR ORGANIC METALS

Novel pi-extended thiophene-fused TCNQ-type and DCNQI-type acceptors have been synthesized from the corresponding quinones by reaction with Lehnert's reagent and bis(trimethylsilyl)carbodiimide (BTC), respectively. Additionally, an example of the little-known hybrid TCNQ-DCNQI-type acceptor has also been obtained. The cyclic voltammetric data of the novel acceptors reveal two different behaviors for these molecules. The TCNQ-type derivatives exhibit a two-electron single-wave reduction to the dianion, as confirmed by controlled potential coulometry analysis. The DCNQI-type derivatives display two reduction waves to the corresponding radical anion and dianion. The same behavior is shown by the hybrid TCNQ-DCNQI derivative. The acceptor ability is related to molecular planarity, and a comparative crystallographic study involving TCNQ-type and DCNQI-type derivatives (6a, 7a, and 8a) has been performed.