Pergamon

Polyhedron Vol. 16, No. 6, p. 993, 1997 Copyright © 1996 Published by Elsevier Science Ltd

Printed in Great Britain. All rights reserved 0277-5387/97 $17.00+0.00

BOOK REVIEWS

Metal Complexes in Aqueous Solutions, by A. E. Martell and R. D. Hancock, 253 pp., Plenum, New York, 1996, $59.50, ISBN 0-306-45248.

If you are one of those chemists who is suspicious of numeri- cal data and trusts only in the formation of crystals, you will learn a lot from this book. The measurement of formation constants often baffles outsiders. Complicated equilibria are described, even more complicated computer programs are run, and some numbers emerge into the light of publication, there to slumber peacefully for evermore. This book shows it need not be like that. We now have this integrated account of the whole subject of the thermodynamics of metal com- plexes in aqueous solution. It reads coherently and ration- alizes the subject in a way that will teach experts and novices alike more than most other books in this area.

The authors have essentially expanded and modernized their 1989 Chemical Review article. The first three substantial chapters present an orderly development of why some ligand-metal complexes are more stable than others. Steric effects, enthalpy and entropy contributions, ligand field effects, hardness and softness, chelate effects and inductive effects are introduced when appropriate, and data are sum- marized with numerous clear structural diagrams and graphs. Some complex structures have been redrawn by the authors from literature data, giving a homogeneous style to the diagrams' appearance and often improving on the pic- tures provided by the original crystallographers.

The rational argument as to what effect generates what result is presented most persuasively by a series of examples. Just when you think one trend is safely established, another set of complexes is produced that bucks that trend, but the new anomaly can then be explained by some other devel- opment. Sceptics may think this all sounds rather like special pleading. After all, every complex has its own peculiarities, and nobody expects simple rules to apply in complicated situations. There is little discussion of kinetics, or of ligand synthesis, and many of the examples come from the authors' own research, with some other active groups being less fre- quently cited. Nevertheless, the whole story is very effective, and readers will find here an excellent rationalization of why chemists should select particular ligands to react with particular metals, and not select other combinations.

The second half of the book uses the principles already developed to design appropriate complexes for medicinal and radiopharmaceutical applications of metal complexes and to rationalize selected aspects of metallobiochemistry. The layout of these chapters is that of a review ordered by metals rather than ligands, and it is noticeable that various biological constraints now enter the argument. There is a certain amount of jargon, so that you will need to know what a myocardial pervasion agent is, and there is a rather elementary discussion of general technetium chemistry which could have been taken for granted. However, the principles the authors developed earlier allow us to see why, for exam- ple, hydroxide ions are bound to zinc effectively in carbonic anhydrase when the binding is much weaker in ordinary aqueous solutions. There are also five effective pages on magnetic resonance imaging. This would be a good intro-

duction to the field for novices, but this section in particular is bound to be obsolete soon, whereas the principles of ligand design will remain valuable for a very long time to come.

The last chapter is a clear account of how to measure stability constants. Expert readers will probably know this already, and the topic is covered for novices elsewhere, but this account is certainly very clear.

There are a few minor mistakes, like the representation of pyridine as C6HsN (p. 34), and the assertion on p. 1 that there is a glossary for technical terms in the Appendix (there is neither a Glossary nor an Appendix). The index is really terrible, even by the standards of chemistry books. For one thing it is too brief, and the selection of entries is perverse. Successive entries feature Desferriferrioxamine (that is what we used to call desferrioxamine), DFO (an abbreviation of the previous entry), AH °, AS ° and Dibenzo-30-crown-10. I wonder when chemistry publishers will realize that indexes are supposed to be helpful rather than entertaining.

PETER THORNTON Queen Mary and Westfield College,

London E1 4NS, U.K.

Energeties of Organometailic Species, edited by J. A. Mar t inho Simfes, N A T O ASI Series: Series C: Math- ematical and Physical Sciences, Vol. 367. xii + 442 pp. Kluwer Academic Publishers, Dordrecht 1992. Price: not stated. ISBN 0-7923-1707-6.

The days are long gone when organometallic compounds of the transition metals were automatically regarded as "unstable", now we know a bit more about thermodynamic and kinetic stability. But how strong are the bonds? This volume, a collection of 20 papers by participants at a 1991 Study Institute, sets out to answer this.

It is a measure of the sophistication attained nowadays that a large majority of papers are not concerned with either classical combustion or solution methods, although one of these latter is an important study of f-block thermochemistry (T. J. Marks). Instead, use is made of equilibrium methods, kinetic methods; short-lived species are studied by voltam- metry. Mass spectra and other methods are employed in the gas phase. How do gas phase and solution data relate? Two papers show us. Concepts such as bond enthalpy trans- ferability are explored (J. A. Connor). Quantitative theor- etical calculations are reported. The overall impression is that this is a diverse and increasingly sophisticated field. Much of this material has by now been published in the learned journals. The benefits of such a meeting are obviously to those who attend the Institute, but also subsequently to the non-specialists who read these proceedings and obtain an overall view under one cover, a state-of-the-art snapshot, not easily obtained by reading the literature.

SIMON COTTON Uppingham School,

Uppingham, Rutland LE 15 9QE

U.K.

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