The Radical Anions of Some Substituted [2.2]Paracyclophanes

✍ Scribed by Peter Fürderer; Fabian Gerson; Hiroaki Ohya-Nishiguchi; Ingrid Böhm; Henning Hopf

• Publisher: John Wiley and Sons
• Year: 1979
• Tongue: German
• Weight: 379 KB
• Volume: 62
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19790620810

✦ Synopsis

Abstract

The radical anions of the following substituted [2.2]paracyclophanes have been characterized by ESR. and ENDOR. spectroscopy: 4, 16‐dicyano‐ (o‐2), 4, 12‐dicyano‐ (p‐2), 4,5,12,13‐tetracyano‐ (3) and 4,5,12,13‐tetrakis (alkoxycarbonyl)‐ [2.2]paracyclophanes (4‐R, where R = Me, Et, i__Pr or t__Bu is the ester alkyl group); 4,5‐bis(methoxycarbonyl)[2.2]paracyclophane‐12, 13‐dicarboxylic anhydride (5); [2.2]paracyclophane‐4,5:12, 13‐tetracarboxylic bisanhydride (6) and bisimides (7‐R, where R = H, D, Me or Ph is the substituent at the imide N‐atom). Comparison of the hyperfine data for these radical anions with those for analogously substituted derivatives of benzene indicates that the most prominent coupling constants are approximately halved on passing from the latter to the former. Lowering of the symmetry, as a consequence of ion pairing, has been observed for the radical anions 4‐iPr\documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document} and 4‐tBu\documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document} associated with the counterion K⊕ in 1,2‐dimethoxyethane at 183 K, but not for 4‐Me\documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document} and 4‐Et\documentclass{article}\pagestyle{empty}\begin{document}$^{\ominus \atop \dot{}}$\end{document} under the same conditions. This result suggests that the migration of K⊕ between the preferred sited in two equivalent ion pairs is slowed down by the steric hindrance arising from the bulky __i__Pr and __t__Bu ester groups.