Electron spin resonance investigation of the photolysis of tert-butylnitrobenzenes and (trimethylsilyl)nitrobenzenes

The photolysis of isomeric (trimethylsilyl)nitrobenzenes and of tert-butylnitrobenzenes produces arylalkoxynitroxide radicals which have been studied by ESR spectroscopy. Relative values of a_N suggest that the p-trimethylsilyl group exerts an overall withdrawing effect while the m-trimethylsilyl group has the opposite effect. The value of a_N for the o-trimethylsilyl radical indicates that steric interaction with the nitro group is probably minimal. o-(Trimethylsilyl)nitrobenzene free radical anion has been prepared ; its a_N value suggests that steric interaction between groups on the aryl ring is also small in this case. © 1969.