| Résumé | Some 3-substituted diazirinyl radicals, RC=NN·, have been generated by photolysis of the parent bromides in the presence of hexa-n-butylditin. The principal EPR parameters for 3-alkyldiazirinyl and 3-phenyldiazirinyl are similar: aN(2N) = 7.8 G, g = 2.0042. INDO calculations give 14N and 13C hyperfine splittings in good agreement with experiment. Diazirinyls are Π radicals, the two nitrogens' 2pz atomic orbitals making the major contribution to the semioccupied orbital. Diazirinyls decay with second-order kinetics to yield the corresponding nitrile. Like other N-centered three-membered ring radicals, they do not form nitroxides. Studies on the products of reaction of aziridinyl, CH2CH2N·, with tert-butylperoxy have revealed that a nitroxide is probably formed, but it decomposes (to ethylene and NO) too rapidly for it to be detected. It is suggested that analogous processes occur with diazirinyls and other N-centered three-membered ring radicals. © 1979 American Chemical Society. |
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