The Polanyi Lecture. Radical–radical reactions: kinetics, dynamics and mechanisms

Abstract

Three facets of radical–radical reactions are examined: their kinetics, i.e. the rates at which such reactions proceed; their dynamics, i.e. the detailed nature of reactive collisions between radicals; and their mechanisms, i.e. the products which are given when more than one reactive channel is energetically accessible. The goal is to show how information about each of these attributes of radical–radical reactions helps to illuminate the fundamental character of radical–radical collisions. The connecting thread, in the spirit of Michael Polanyi's pioneering work, is the form of the potential-energy surface or surfaces that control the collisions. The general themes are illustrated by reference to studies of particular systems, especially those which have been, or are being, investigated in the author's laboratory. Every effort is made to assess the current level of understanding, to indicate areas where that understanding is deficient, and to suggest how our knowledge of radical–radical reactions might be improved.