Electron spin resonance studies of the anion radicals of pyridinium bis(alkoxycarbonyl)methylides

Abstract

By means of e.s.r. spectroscopy, it was found that short-lived anion radicals of pyridinium bis(alkoxycarbonyl)methylides have unusual hyperfine splittings and a unique unsymmetrical electronic structure. The hyperfine splitting constants of these anion radicals agree well with the spin densities from MO calculations using the modified Steinberger–Fraenkel method. On the other hand, the hyperfine splitting constants of the cation radicals can be explained by the usual MO calculations.