Ab initio study of propyl radicals

Abstract

The UHF method has been used to show that the most stable conformation of the n-propyl radical is when the methyl group is in a plane perpendicular to the plane of the methylene group, contrary to experiment and previous SCF calculations. The hindered rotation coordinate for the methylene group is calculated by including the zero-point energies of each conformation within the adiabatic approximation. The most stable conformation is now when one of the C_β—H bonds is in the plane perpendicular to the plane of the methylene group. These calculations suggest that C—CH₃ hyperconjugation is at least as significant as C—H hyperconjugation. A study is made on the isopropyl radical to investigate the motions of the equivalent methyl groups. This radical is interesting, since the muonated derivative has been studied.