42858-85-5Relevant articles and documents
Powerful oxidizing properties of a planar [8]annulene: Tetrakis(perfluorocyclobuta)cyclooctatetraene) and its radical anion
Gerson, Fabian,Huber, Walter,Merstetter, Pascal,Persy, Gaby,Soulen, Robert L.,Spoendlin, Christoph,Wirz, Jakob
, p. 1434 - 1444 (1999)
The central eight-membered ring of tetrakis(perfluorocyclobuta)cyclooctatetraene (1) is flat both in the crystal and in solution, but tetrakis(perfluorocyclopenta)cyclooctatctracne (2) assumes a tub shape similar to that of parent cyclooctatetraene. This sterically induced structural difference strongly affects the physical properties of compounds 1 and 2. The first and second reduction potentials of 1 in solution, + 0.79 and + 0.14 V vs. SCE, are considerably more positive than the corresponding values, + 0.20 and - 0.21 V, of 2. Accordingly, mere contact with Hg metal in N,N-dimethylformamide converts 1 to an unusually stable radical anion 1'- that is persistent in air. The temperature- independent coupling constant, a(F) = + 0.320 mT, of the sixteen equivalent [β19F-nuclei in 1- is much smaller than the expected value, and the g factor of 1'- is markedly lower than those generally found for structurally related radical anions. In contrast, the characteristic data for 2-, generated from 2 with K metal in 1,2-dimethoxyethane, comply with the expected data. The coupling constants a(F) = + 0.976 and +0.935 mT, each of eight β-19F-nuclei in 2-, average +0.951 mT upon raising the temperature from 220 to 260 K. The gas-phase electron affinity of 1, A = 3.4 ± 0.2 eV, which was estimated from the reduction potential in solution and from charge- transfer absorption spectra obtained from a series of methylated benzenes and naphthalenes, is among the highest known for neutral organic molecules.
