Line-width alternation in the e.s.r. spectrum of barium acenaphthene semiquinone in DME

Abstract

The e.s.r. spectrum of barium acenaphthene semiquinone in DME has been studied over the temperature range –20 to +100°C. Marked line-width alternation has been found. It is suggested that this is due to a modulation of the ring proton hyperfine splitting constants and that this arises from the movement of the barium cation between equivalent sites which are unsymmetrically located with respect to the two anions. The possible sites are discussed. Evidence is reviewed which strongly indicates that this barium semiquinone complex is a solvent-shared species.