STUDY OF DIALKYLTELLURIUM RADICAL CATIONS BY ELECTRON-SPIN-RESONANCE SPECTROSCOPY

The ESR spectra are reported for the radical cations (CH3)2Te+ and (C2H5)2Te+ produced by exposure of very dilute solutions of (CH3)2Te or (C2H5)2Te in CFCl3 to Co-60 gamma-rays at 77 K. The results show that the species are pi-radicals and that the unpaired electron is strongly confined to the tellurium 5p(z) orbital. As expected for such pi-radicals, g(x) > g(y) > g(z) almost-equal-to 2.00, e.g. for (CH3)2Te+, g(x) = 2.26(0), g(y) = 2.13(6) and g(z) = 1.99(0). 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)2Te in CFCl3 were similarly irradiated some evidence in the ESR spectrum was found for the presence of the sigma* three-electron bonded species [CH3)2Te-Te(CH3)2]+.