The radical anion of 1,2:9,10-dibenzo[2.2]paracyclophane.. An ESR, ENDOR, and TRIPLE resonance study

✍ Scribed by Fabian Gerson; William B. Martin Jr.; Henry N. C. Wong; Chin Wing Chan

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: German
• Weight: 589 KB
• Volume: 70
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19870700110

✦ Synopsis

The radical anion of 1,2:9,10-dibenzo[2,2]paracyclophane (3) has been studied by ESR, ENDOR, and TRIPLE resonance spectroscopy under a variety of experimental conditions. The coupling constants of the eight protons in the deck-benzene rings, and of the four inner and four outer protons in the side-benzene rings are 0.234, 0.123, and 0.036 mT, respectively (solvent: 1,2-dimethoxyethane; counterion: K' ). All three values have the same sign which is predicted to be negative. Comparison of the largest coupling constant (0.234 mT) with the corresponding value (0.297 mT) for the radical anion of the parent [2.2]paracyclophane (1) points to similar nodal properties of the singly occupied orbitals in 1and 3' . Notwithstanding this similarity, 3seems to associate less readily than 1with alkali metal counterions, since tight ion pairs of 3' with Kf are formed only in solvents of low solvating power. Effects of conformational changes on the ESR spectra, such as those previously observed for the radical anion of [2.2]paracyclophane-1,9-diene (2), are not apparent for 3in the temperature range of investigation. Hyperfine data are also reported for the radical anion of a derivative 4 which has a CH, substituent in one of the side-benzene rings of 3.

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Denoted in [I] as 1,2 :7,8-dibenzo[2.2]paracyclophane.