The problem of conjugation through key heteroatoms in arene-2,1,3-X-diazoles (X=O, S, Se)
Potassium metal and an electrochemical method are used to prepare anion radicals from benz-2,1,3-oxa-, -thia-, and -selenadiazoles, and also from naphtho-1,2-furazane and naphtho-1,2-selenadiazoles. The EPR spectra of these anions are analyzed, and the results compared with the calculated distributions of spin densities in the anions. It is concluded that the key heteroatoms in the molecules of the compounds investigated participate in conjugation in a definite way. This conclusion is also based on analysis of the electronic absorption spectra of arene-2,1, 3-X-diazoles. Apparently the distribution of spin density in the heterocyclic ring does not change substantially from benzologs to naphthologs.