Anisotropic fluorine and proton hyperfine interaction and motional effects in the electron spin resonance spectrum of the β,β,β-trifluoroethyl radical (CF3CH2⋅) in an argon matrix at 4.2 K

Abstract

The electron spin resonance spectrum of the β,β,β-trifluoroethyl (CF3CH2⋅) radical has been measured in a polycrystalline argon matrix at 4.2 K. The radical was produced in situ by photolysing the corresponding iodide. An analysis of the spectrum leads to a complete evaluation of the anisotropies in the g and hyperfine interaction tensors of the spin Hamiltonian for the radical. The analysis is confirmed by a computer simulation of the observed line shapes, and the following magnetic parameters were evaluated: gx=2.0021, gy=2.0020, gz=2.0026, AxH(α) =23.7±0.1, AyH(α) =22.3±0.1, AzH(α) =30.9±0.1, AxF(α) =17.7±0.1, AyF(α) =20.4±0.1, and AzF(α) =48.0±0.1 G. A discussion of the above results provides an understanding of the mechanism of electron spin delocalization to the β-fluorine atoms, as well as additional information on the conformation of the α-substituent nuclei and the effects of their motion on the line shapes of the spectrum.