Dications of fluorenylidenes: conformational and electronic effects on the paratropicity/antiaromaticity of fluorenyl cations with cyclic substituents

摘要

oxiation of tetrabenzofulvalene derivtives 1-5 containing fluorenylidene and 5-7-0membered rings resulted in the formation of dications which are effectively fluorenyl cations with perpendicular cyclic substituents. The observed paratropicity of the fluorenyl cation in these system is attributed to an antiaromatic ring current, after evaluation of the effects of geometry, charge density, and polarity of the medium, and is dependent on the geometry and electronic character of the cyclic substituent.