An ab initio study of some free-radical homolytic substitution reactions at sulfur, selenium and tellurium

Abstract

Ab initio molecular orbital calculations using pseudopotential basis sets and electron correlation (MP2, QCISD) predict that homolytic substitution by methyl, silyl, germyl and stannyl radicals at the chalcogen atom in methanethiol, methaneselenol and methanetellurol, with the expulsion of methyl radical, proceeds smoothly. With the exception of dimethyl- λ 4-tellanyl at the MP2 and QCISD levels of theory, no hypervalent (9-E-3) intermediates were located in any of the reactions in this study. Reactions of germyl and stannyl radicals at methaneselenol and methanetellurol are predicted to be reversible.