Electron spin resonance and ENDOR reinvestigation of iminoxyl radicals from 1-halogenofluorenone oximes

Abstract

In a reinvestigation of 1-halogenofluorenone iminoxyl radicals, ¹H and ¹⁴N ENDOR spectra have been obtained from the chloro-compound. The e.s.r. spectra of the series of radicals (X = H, F, Cl and Br) have been analysed in detail by means of computer-fitting procedures. Contrary to previous interpretations, the spectra of the chloro-compound must be attributed to a single species, namely the anti form. Magnitude and sign of the coupling constant of the proton in position 8 are in accordance with through-space spin-density transfer. The effects of halogen substitution on the ENDOR response are discussed.