AbstractThe radical anion of dibenz[b,f]oxepin has been investigated by esr spectroscopy and the relative coupling constants compared with dibenzo[b,f]thiepin. In both cases assignments were obtained using a theoretical method (INDO). In addition radicals from dibenzo[b,f]thiepin sulfoxide and sulfone could be detected and, unusually, the free electron density on carbon atoms of the radical anion containing a sulfonyl group is larger than that on carbons of radical anions containing a sulfide or a sulfoxide group.