Electron spin resonance evidence for greatly enhanced hyperconjugation in radicals containing tin, phosphorus, and arsenic

Abstract

Direct e.s.r. evidence for strong hyperfine interaction with phosphorus, arsenic, or tin atoms β to redical centres is presented, which is linked with the large rate enhancements detected by others when such groups are β to aromatic ring systems; the interaction is shown to be hyperconjugative rather than to involve outer d orbitals.