The Description of Molecular Structure

The classical description of molecules is based on their empirical formula, constitution, configuration, and conformation. In this chapter, we shall briefly review these concepts and also that of chirality, as they are commonly understood. A discussion of some structural features of flexible molecules indicates that purely geometrically based concepts of configuration, conformation, and chirality so well as some currently used modifications of those concepts cannot be universally applied in a consistent manner. We then propose a unified conceptual framework for stereochemistry, including new definitions of stereoisomerism and chirality. These definitions are based on chemistry, rather than on geometric models, and have an unambiguous meaning for all molecules.