Principles, Definitions, Terminology, and Orbital Analysis of Lewis Base-Lewis Acid Interactions Leading to Catalysis

This chapter traces the historical development of Lewis's concepts of acids and bases, to chronicle various refinements and presents a number of modern interpretations of donor-acceptor interactions. It provides a conceptual framework that allows a clear formulation of what exactly "Lewis base catalysis" constitutes. As the application of quantum mechanics became more and more important to understanding structure and reactivity of organic molecules, the need to adapt Lewis's definitions of acids and bases in terms of molecular orbital theory became apparent. The expression of the interaction in quantum-mechanical terminology allowed R.S. Mulliken to recognize a number of significant consequences that were inaccessible to Lewis and his successors because of the limitations of earlier structural theories. The chapter also explores the most successful analyses beginning with an expanded presentation of the Mulliken valence bond approach through primarily empirical to highly theoretical analyses.