F. Gerson, W. Martin, G. Plattner
1976
Citations
0
Influential Citations
17
Citations
Journal
Helvetica Chimica Acta
Abstract
ESR. studies are reported for the radical anions of 5,6-didehydro- and 5,6,11,12-tetradehydro-dibenzo[a,e]cyclooctene (III and IV, resp.), in addition to that of dibenzo[a,e]cyclooctene (II) itself, the spectrum of which has been reexamined. Comparison of the proton and 13C coupling constants for II·⊖, III·⊖ and IV·⊖ indicates that the three radical anions do not differ greatly in their electronic and molecular structures. This statement implies that II·⊖ should also be substantially planar, i.e., the tub-shaped eight-membered ring in II is expected to flatten on passing from the neutral molecule to its radical anion. Support for postulating such a change in geometry, analogous to that encountered with the parent cyclooctatetraene (I), is provided by INDO calculations.