The radical cations of bicyclo[6.1.01nonatriene (1a) and several derivatives (1b-f) have been generated by photoinduced electron transfer in solution. The radical cation 3a, derived from the parent, has a weakened cyclopropane bond with spin (and charge) density at C1 and C8. Electron return in singlet pairs regenerates la, whereas triplet recombination gives rise to cyclononatetraene (6). Electron-withdrawing substituents at C9(Cl, 1c) cause spin and charge to be restricted to the triene moiety. The 9,9-diphenyl derivative 1d undergoes electron-transfer-induced rearrangement to 7-(β,β-diphenylethenyl)-cycloheptatriene, whereas the spirofluorene derivative 1f is converted to a barbaralane derivative 9f. The homoaromatic radical cation 10f is suggested as an intermediate in this remarkable rearrangement.
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry