R. L. Soulen, J. Wirz
Aug 1, 1985
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Journal
Journal of Fluorine Chemistry
Abstract
Abstract Tetrakis(tetrafluorocyclobuta)cyclooctatetraene (PCOT) (C 16 F 16 ) is a unique centrosymmetric molecule with the eight carbon atoms of the inner ring planar. Bond length alternation within the 8 membered ring is only ±0.036 Ā with the longer bond exocyclic to the cyclobutene rings. These structural features will be contrasted with typical perfluoroalkyl substituted benzene and cyclooctatetraene derivatives. PCOT in acetonitrile undergoes rapid and reversible electrochemical reduction at positive 0.79 and 0.14 volts, thus it is one of the most powerful neutral organic oxidants known. Many common organic solvents, ferrocene and elemental mercury are rapidly oxidized by PCOT at room temperature. The absence of a ring flattening barrier (est. 12–22 K cal/ mol) and the 16 F atoms provide theoretical rationale for these observations. The HeI δ photoelectron spectra of PCOT (Ip = 10.3, 11.9 and 12.9 eV) suggests that the molecule retains the planar D 4H symmetry in the gas phase and that the unknown parent hydrocarbon would be air sensitive. Measurements of charge transfer maxima with a variety of donor aromatic hydrocarbons reveal that PCOT may possess the highest electron affinity for any neutral molecule. As expected, PCOT is a powerful dienophile in Diels-Alder reactions.