Influence of topology on the long-range electron-transfer phenomenon

Intramolecular electron-transfer phenomena in the radical anions derived fr om the partial reduction of diradicals (E,E)-p-divinylbenzene-beta,beta'-yl ene bis(4-tetradecachlorotriphenylmethyl) diradical (1) and (E,E)m-divinylb enzene-P,P'-ylene bis(4-tetradecachlorotriphenylmethyl) diradical (2) have been studied by optical and ESR spectroscopy. The synthetic methodology use d allows for complete conatrol of the geometry of diradicals 1 and 2, which have para and meta topologies, respectively, as well as of their E/Z isome rism. This fact is used to show the influence of the different topologies o n the ease of electron transfer, which is larger for the para than for the meta isomer, in which a small or negligible electronic coupling is observed . A related monoradical compound (E)-bis(pentachlorophenyl) [4-(4-bromophen yl-beta -styryl)-2,3,5,6-tetrachlorophenyl]methyl radical (3), which has on ly one such redox site, has also been obtained and studied for comparison p urposes.