The barriers to internal rotation for muonic-substituted ethyl radicals

Abstract

By fitting of the observed temperature dependence of the β-hyperfine muon–electron interaction to a theoretical model for the muonic radicals CH₂MuĊH₂, CHDMuĊH₂, CHDMuĊD₂ and CD₂MuĊD₂ values for the barrier height V₂ restricting internal rotation are calculated. A decomposition of the barrier into pair interactions indicates the isotope effect upon the barrier to be in the sequence V^DD₂ < V^DH₂ < V^HH₂ < V^MuD₂ < V^MuH₂. On this basis the barriers to internal rotation for the radicals CH₂MuĊD₂ and CD₂MuĊH₂ are predicted to be of the order 3076 and 3186 J mol^–1, respectively.