Hyperfine coupling constants of the 2-chloroethyl and related radicals

The electron resonance spectra of several fluorine and chlorine substituted alkyl radicals have been recorded in fluid solution. We have found that beta-chlorine hyperfine splittings are often larger than those of alpha-chlorines. The 2-chloroethyl radical has a preferred conformation in which the chlorine atom is eclipsed by the p-orbital containing the unpaired electron suggesting an unsymmetrical bridged structure for this species; relatively free internal rotation is observed in the 2-fluoroethyl radical.