Reactions of coordination compounds

It is apparent, from the above short survey, that kinetic studies have been restricted to the decomposition of a relatively few coordination compounds and some are largely qualitative or semi-quantitative in character. Estimations of thermal stabilities, or sometimes the relative stabilities within sequences of related salts, are often made for consideration within a wider context of the structures and/or properties of coordination compounds. However, it cannot be expected that the uncritical acceptance of such parameters as the decomposition temperature, the activation energy, and/or the reaction enthalpy will necessarily give information of fundamental significance. There is always uncertainty in the reliability of kinetic information obtained from non-isothermal measurements. Concepts derived from studies of homogeneous reactions of coordination compounds have often been transferred, sometimes without examination of possible implications, to the interpretation of heterogeneous behaviour. Important characteristic features of heterogeneous rate processes, such as the influence of defects and other types of imperfection, have not been accorded sufficient attention. 

Mechanistic aspects of the photochemical reactions of coordination compounds. M. S. Wrighton, Top. Curr. Chem., 1976, 65, 38-104 (196). 

It is salutary to read the comment, At the time when I became interested in the reactions of coordination compounds the formula of not a single aquo complex was known with certainty, made by Taube in a recent review (364). In marked contrast, this review is predominantly concerned with the intimate detail of the mechanisms of sol-... 

Wrighton, M. S. Mechanistic Aspects of the Photochemical Reactions of Coordination Compounds. 65,37-102 (1976). 

O Brien, P. (1983). Polyhedron 2, 223. An excellent review of racemization reactions of coordination compounds in the solid state. 

In this chapter, a survey of the enormously broad area of reactions of coordination compounds will be presented, and some of the basic mechanisms of the reactions will be presented. However, reactions of coordination compounds is such a very broad area that this chapter (as would be the case of any chapter) can present only the basic concepts and an elementary introduction to the field. More detailed coverage will be found in the references listed at the end of the chapter. The classic books in the field are Basolo and Pearson (1974) and Wilkins (1991), which present excellent and detailed reviews of the literature. We begin the chapter by illustrating some of the synthetic methods that have been useful for synthesizing coordination compounds. 

The replacement of one ligand by another is the most common type of reaction of coordination compounds, and the number of reactions of this type is enormous. Some are carried out in aqueous solutions, some in nonaqueous media, and others can be carried out in the gas phase. One such reaction is... 

As in many areas of chemistry, there are reactions of coordination compounds that are not what they appear. For example, the reaction... 

Espenson, J. H. (1995). Chemical Kinetics and Reaction Mechanisms, 2nd ed. McGraw-Hill, New York. A book on chemical kinetics, much of which is devoted to reactions of coordination compounds. Highly recommended. 

Wilkins, R. G. (1991). Kinetics and Mechanisms of Reactions of Transition Metal Complexes. VCH Publishers, New York. Contains a wealth of information on reactions of coordination compounds. 

Much of Chapter 20 was devoted to the description of mechanisms of reactions of coordination compounds with emphasis on substitution reactions. Because there are numerous aspects of oxad reactions that are different from those involving substitution, we will address some of the mechanistic aspects of oxad reactions briefly in this section. 

Most reactions of coordination compounds can be classified as either substitutions or oxidation-reductions. The classic book by Basolo and Pearson19 discusses both types in detail. The oxidation-reductions can occur either by simple electron transfer or by atom transfer. Taube s work on the reduction of cobalt(IJI) complexes by Cr11 is especially important in this regard. Among the many reactions which he has studied, the best known, perhaps, is20... 

Reactions of coordination compounds in the solid state have been studied extensively for many years. There are very few cases of two complexes reacting with each other the important examples are those in which a complex loses one or more volatile ligand molecules upon heating, or which undergoes rearrangement or racemization without loss of a volatile component. If a volatile ligand is lost, several different results may ensue ... 

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