ESR-Spectroscopic Investigation of Radical Cations,Radical Anions,and Radical Trianions of Didehydro[n]annulenes

The didehydron]annulenes 1 (n = 14), 2 (n = 18), and 3 (n = 22) are oxidized to radical cations. Reduction of the title compounds leads to radical anions and, in the case of 2 and 3 , to radical trianions. The hyperfine data of the paramagnetic derivatives are rationalized in terms of the occupation of n-membered (n = 14, 18, 22) π-perimeter MO's (HOMO, LUMO, NLUMO). The contact-ion pairs of the radical anions show unexpectedly large alkali-metal coupling constants.