Substituent effects on the rotational strength of the n–π* carbonyl band

Abstract

The quantitative contribution of a substituent in the α-axial position of a cyclohexanone derivative to the rotatory strength of the 3000 Ån–π* carbonyl band is discussed. Calculations of the extended Hückel type on a model compound indicated the importance of delocalisation through the σ framework and predict variation of rotatory strength with electronegativity and overlap. Observed values of substituent contributions are discussed in terms of these predictions.