An annulene TCNQ derivative with rather weak acceptor properties

Reaction of the bridged [14]annulenequinone, trans-10b, 10c-dimethyl-10b, 10c-dihydropyrene-2,7-quinone (12), with malononitrile in the presence of pyridine and TiCl₄ gave 68% of the deep-purple extended TCNQ derivative, α,α,α′,α′-tetracyano-trans-10b, 10c-dimethyl-10b, 10c-dihydropyrene-2,7-quinodimethide (13). In solution, quinodimethide 13 appears to form a complex with diethylamine, but is too weak an electron acceptor to form complexes with tetrathiafulvalene, TTF, and related donors. The reduction potential of 13 was substantially lower than that found for TCNQ itself, and in properties 13 behaves more like a benzannelated TCNQ derivative, e.g., α,α,α′,α′-tetracyanopentacene-7,14- quinodimethide (11), than a pyrene derivative, e.g., α,α,α′,α′-tetracyanopyrene-2,7- quinodimethide (6). This is in agreement with molecular orbital calculations, which indicate that the LUMOs of 13 and 11 are approximately 0.6 eV higher in energy than those for 6 and TCNQ.