Electron spin resonance spectra and conformations of radicals produced from cycloalkanols

Abstract

Cyclic radicals of the type [CH₂]_nĊ—OH with n varying from 3 to 7 have been produced by photolysis and their e.s.r. spectra recorded over a wide temperature range.

Information about the conformations of these systems is obtained. For n= 3, 4 the rings are stable in a planar configuration. For n= 5 the preferred conformations are the chair and the twisted chair interconverting with measurable speed. For n= 6 the radical interconverts among symmetrical and unsymmetrical twisted chair conformations. For n= 7 a single unsymmetrical conformation seems to be preferred, indicating, however, some degree of flexibility. The temperature dependence of the OH-proton coupling constants is discussed in the cases in which it is measurable (n= 3, 6).