Conformational analysis of carbonyl and thiocarbonyl ethyl esters: The HC(X) (X, Y = O or S) internal rotation

Abstract

AbstractThe internal rotation in the HC(X)YCH2CH3 (X, Y = O or S) series of molecules was studied by the ab initio SCF‐MO method using 3‐21G and 3‐21G + d(ζ = 0.65S) basis sets. Energies and structures of several conformations of these molecules, determined by gradient geometry refinement, are reported and used to assess the effects of oxygen‐by‐sulphur substitution on molecular properties. The nature and relative importance of intramolecular interactions involving both the CH2CH3 and the HC(X)Y (X, Y = O or S) fragments are also discussed. © 1992 by John Wiley & Sons, Inc.