Substitution Reactions of Inert-Metal Complexes—Coordination Numbers 4 and 5

Abstract

Among reviews of general interest are two very useful accounts by van Eldik and co-workers on the application of high-pressure methods to kinetics and mechanisms.^(1,2) Reference 1 contains a valuable compilation of activation and reaction volumes of inorganic reactions, and considers their interpretation for various reaction types. Reference 2 dwells more on the experimental details and design of equipment, but also contains illustrations from reactions of square-planar compounds. A review by Blandamer and Burgess on a thermochemical approach to solvation of transition metal complexes is also of relevance to this section, ⁽³⁾ and a report by Burgess and Pelizzetti on medium effects points out the importance of solvation in reactions of square-planar compounds, emphasizing the role of leaving-group salvation.⁽⁴⁾ Second-sphere coordination of cyclodextrins to square-planar complexes has been surveyed by Stoddart and co-workers.⁽⁵⁾The potential importance of such interactions is illustrated by a report that the complex ion [Pt(bipy)(NH₃)₂]²⁺ can form a bipy-crown ether interaction which then protects it from some photochemically induced reactions.⁽⁶⁾