Role of crystallography in understanding reactions in the solid state

Abstract

In recent years, X-ray crystallography has been extensively employed to study solid-state reactions. It is found that the initiation and progress of many of these reactions is governed by structural and geometric factors. Such reactions are known as topochemical reactions. While, in general, solid-state reactions take place to polycrystalline samples, some are known to occur in single crystals without a breakdown of the lattice. The reason for this is the close similarity in the reactant and product structures. These reactions are termed topotactic reactions. In this brief review, a few examples of topochemical and topotactic reactions are discussed, and the important role of crystallography in elucidating their mechanism highlighted.