The Radical Ions of Dipleiadiene (Dicyclohepta[de,ij]naphthalene) and Its 12b,12c-Homo Derivative. An ESR and ENDOR study
✍ Scribed by Rainer Bachmann; Fabian Gerson; Pascal Merstetter; Emanuel Vogel
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- German
- Weight
- 449 KB
- Volume
- 79
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Abstract
The radical anions and the radical cations of dipleiadiene (dicyclohepta[de,ij]naphthalene; 1) and its 12b, 12c‐homo derivative 2 were characterized by ESR and ENDOR spectroscopy. Their singly occupied orbitals are related to the degenerate nonbonding MOs of a 16‐membered π‐perimeter. The π‐spin distribution over the perimeter is similar in the radical cations 1^.+^ and 2^.+^, and an analogous statement holds for the radical anions 1^.−^ and 2^.−^. However, deviations of the π‐system from planarity lead to a decrease in the absolute values of the negative coupling constants of the perimeter protons in 2^.+^ and 2^.−^ relative to those in 1^.+^ and 1^.−^. The hyperfine data for the perimeter protons in the radical ions correlate with the changes in ^13^C chemical shifts on passing from the neutral compounds to the corresponding diions. It is concluded from the coupling constants of the CH~2~ protons in the radical ions of 2 that the cation 2^.+^ exists in the methano‐bridged form (A) of the neutral 2 (and, presumably, also of the dication 2^2+^), whereas the anion 2^.−^ adopts the bisnorcaradiene form (B) of the dianion 2^2−^.