Radical adducts of para-substituted 1,1-diphenylethylenes: an electron spin resonance study

Abstract

The e.s.r. spectral parameters of the paramagnetic adducts (XC₆H₄)₂ĊCH₂MR_n, formed by reactions of transient R_nM· radicals centred at elements of Groups III–VI with para-substituted diphenylethylenes, are reported. Ring substitution with OCD₃, SCD₃, or SO₂CD₃ affects the hyperfine couplings at the phenyl and methylene protons to only a minor extent, except in the adducts of the benzoyloxyl radical. The present data are inconsistent with the interpretations which attribute the variations of the β-proton splittings in β-substituted ethyl radicals either to bond angle distortions or to the electronegativity of the MR_n substituent.