E.s.r. spectra of some aromatic free radical anions which contain cumulated and unsaturated chains
The free-radical-anions af α,γ-diphenylbutadiene, diphenyldiacetylene, tetraphenylethylene, tetraphenylbutatriene, tetraphenylhexapentaene, dibiphenylene-ethylene and dibiphenylenebutratriene have been produced in solution by reduction with potassium. Well-resolved e.s.r. spectra of the radical-anions have been recorded. Except for tetraphenylethylene the spectra have been completely analyzed and the experimental h.f.s.c. compared with the values calculated by the Hückel and McLachlan methods. For tetraphenylethylene, partial analysis of the spectrum has been achieved and two h.f.s.c. and the total spectrum width have been determined. All attempts to produce the free-radical-anion of tetraphenylallene failed. This has been discussed in terms of the probable electron-affinity of this molecule.