Additivity of conformational energy: Quantum mechanical investigation of fluoro- and bromoalkanes

Abstract

The possibility to use additivity rule [1] for estimation of relative conformational energies of fluoro-and bromo-substituted alkanes is studied. The ability of quantum mechanical methods (HF and MP2) to estimate the additivity increments EThe obtained results have been compared with available experimental data. It is shown that increments are sensitive to the method and basis set used. The arrangement of relative conformational energies for various conformers in the series of polysubstituted fluoro-and bromoalkanes obtained using additivity rule agrees both with experimental findings and quantum mechanical calculations. The results lead to the conclusion that it is possible to work out the quantum mechanically based additivity schemes for investigated compounds.