Spin Distribution and Chemical Reactivity of sigma-Free Radicals

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1. (4-t-Butylphenylthio)(4-methoxyphenyl-1- ^<13>C)diazene, (4-t-butylphenylthio)(4-chlorophenyl-1- ^<13>C)diazene, (4-t-butylphenylthio)(1-naphthyl)diazene, its 1- ^<13>C, 1- ^<13>C-1- ^<15>N, 2, 4-d_2-labled compounds, and(4-t-butylphenylthio)(2-naphthyl)diazene were studied by the ESR method to determined hfs constants of H, ^<13>C, and N nuclei. In the ESR experiments by using nitrosobenzene-1- ^<13>C under electrode oxidation we observed a nitroxide of unknown free radical. Using more dilute solutions the experiment will be continued.2. TRIPPLE resonance ESR technique was unsuccessful to 4-methoxyphenyldiazenyl because of low concentration of the transients.3. Identification of E lines(delta-135)and A lines(delta-133 ppm)in CIDNP spectra from(aryl)(arylthio)diazenes was completed by reference to chemical shifts of authentic 9 chloroarenes(A)and 18 diaryl sulfides(E).Signes of his constants of 1-C and 2-C of 4-methoxyphenyldiazenyl in CIDNP is probably reversal to each other with relative intensity ratio-30 : 1 for 1-C to 2-C.4. Trapping of 4-methoxyphenyldiazenyl by deuterio-tetramethylnitrosobenzene was attempted. The diazenyl-trapped nitroxide was not confirmed, but a nitroxide of unknown radical of higher g-value was detected together with arylphenylnitroxide in a ratio ca. 4 : 1.5. Spin densities on 1-C and 1-N of aryldiazenyl may explain a rate of H-abstraction by aryl radical relative to diazenyl from substituted toluenes.