Study of dialkyltellurium radical cations by electron spin resonance spectroscopy

Abstract

The ESR spectra are reported for the radical cations (CH₃)₂Te⁺ and (C₂H₅)₂Te⁺ produced by exposure of very dilute solutions of (CH₃)₂ Te or (C₂H₅)₂ Te in CFCl₃ to ⁶⁰Co γ-rays at 77 K. The results show that the species are π radicals and that the unpaired electron is strongly confined to the tellurium 5p_z orbital. As expected for such π radicals, g_x > g_y > g_z≈ 2.00, e.g. for (CH₃)₂Te⁺, g_x= 2.26₀, g_y= 2.13₆ and g_z= 1.99₀. Linear correlations between the spin–orbit coupling constants and the g_x, g_y values and between the methyl-group proton hyperfine coupling constants and ionisation potentials for (CH₃)₂X⁺(X = O, S, Se or Te) are presented. When more concentrated solutions of (CH₃)₂ Te in CFCl₃ were similarly irradiated some evidence in the ESR spectrum was found for the presence of the σ* three-electron bonded species [CH₃)₂Te–Te(CH₃)₂]⁺.