NATURE OF THE 9,9'-BIANTHRYL AND 10,10'-DIMETHOXY-9,9'-BIANTHRYL RADICAL-ANIONS

Electrochemically generated 9,9'-bianthryl (BA) and 10,10'-dimethoxy-9 ,9'-bianthryl (DA) radical anions have been studied by means of UV-VIS and ESR spectroscopy. The electronic absorption spectra as well as ES R studies indicate that within the electrochemically generated radical anions the unpaired electron is localized on one of both anthracene s ubunits of the A-A parent molecule. The rate constants for the intramo lecular electron exchange reactions within the radical anions A-A-. we re measured by ESR line-broadening effects. In dimethylformamide rate constants of (4.2 +/- 0.3) x 10(7) s-1 and (2.2 +/- 0.3) x 10(7) s-1 w ere found for BA-. and DA-. at 298 K respectively. The rates have been interpreted in terms of Marcus electron transfer theory and it was fo und that the reactions are strongly nonadiabatic. Theoretical calculat ions verify these circumstances.