INTRAMOLECULAR ELECTRON-TRANSFER BETWEEN TERMINAL 1,4-DIMETHOXYBENZENE UNITS IN RADICAL CATIONS WITH A [2.2](1,4)NAPHTHALENOPHANE, [2.2](1,4)ANTHRACENOPHANE, AND PENTACENE SKELETON

Various radical cations, in which two terminal 1,4-dimethoxybenzene un its:are anellated to [2.2]paracyclophane (2b(.+), 3b(.+)), [2.2](1,4)n aphthalenophane (4d(.+)). and anthracene bridges (5(.+)), have been st udied by ESR and ENDOR spectroscopy. In the syn- and anti-naphthalenop hane radical cations 2b(.+) and 3b(.+) the delocalization of the unpai red electron over both pi-moieties and the distinct difference between the first and second oxidation potentials, Delta E = E-2(0) - E-1(0), are evidence for a substantial intramolecular electronic interaction between, the two electrophores. Extension of the bridge in 4d(.+) and 5 by benzo anellation results in a localized radical cation. Strong in tramolecular electronic interaction between the two electrophores is f ound in the 1,4,8,11-tetramethoxy-pentacene radical cation (5(.+)). Th e syntheses of 4d are described.