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ordinatively saturated, binary complexes to a study of all types of interactions that may take place in multicomponent solutions. Not too many years ago it was considered quite esoteric to take account of the stepwise addition of ligands to a metal ion or to consider the formation of complexes with more than one metal atom or more than one type of ligand. This attitude has changed largely as a result of the publication in 1957 of "Stability Constants," the IUPAC compilation of equilibrium data edited by Bjerrum, Schwarzenbach, and Sillen. The worldwide enthusiasm thus generated for much more detailed investigations of the species present in aqueous solutions is reflected in this book by the author, professor of physical chemistry at Kossuth Lajos University, Hungary. This is an updated (to 1968) English translation of a 1965 Hungarian version. Essentially all of the material covered is concerned with aqueous solution complexes of transition metals, and little mention is made of other solvents or of interactions in strong electrolytes of Group I and II metals ions. The first four chapters deal with the formal description of multistep equilibria, with a strong historical flavor and a bias toward approximate graphical methods of evaluating equilibrium constants. The more recent, but more general, statistical methods employing high-speed computers—e.g., LETAGROP, HALTAFALL, SCOSUS, and SCOGS—are only briefly mentioned and no discussion is given of the optimum strategies for calculations during these methods. The presentation of graphical and numerical methods for hand calculations, however, is clear and comprehensive. A long chapter on experimental methods gives a detailed review of spectrophotometric studies, which is natural considering the author's own research interests. However, only six pages are devoted to potentiometric methods, although most Brônsted acidbase systems and a great many transition metal systems have been studied potentiometrically. Solubility measurements are given only three pages, and nuclear magnetic resonance techniques dismissed in a single paragraph. In most instances, one must return to the original literature for any detailed discussion of actual experimental techniques. Four excellent chapters follow which review recent literature on the chemistry of protonated, mixed-ligand, outersphere, and polynuclear complexes. This material is particularly interesting if one is interested in an overall view of
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ANALYTICAL CHEMISTRY, VOL. 43, NO. 2, FEBRUARY 1971
the current state of knowledge in these aspects of coordination chemistry which have really been well-defined only for a short time. Between two chapters of this otherwise fine review is an unfortunate six-page chapter entitled "Formation and Stability of AquoComplexes" which attempts to review ionic hydration but only further mystifies an already difficult subject, and should have been discarded. The final chapter, primarily concerned with correlations between stability constants and properties intrinsic to the central ion or the ligand, may prove quite useful in predicting data for systems \vhcre no experimental work has yet been done. The author envisions three main directions for future equilibrium studies: "(1) Determination of formation enthalpy and entropy of different species; (2) study of protonated, mixed-ligand, polynuclear, and outer-sphere complexes besides that of mononuclear binary species; and (3) study of complex equilibria in nonaqueous media." The greatest strength of this book is the author's clear grasp of real chemical systems, and his refusal to become overwhelmed by general formalisms, even when they appear elegant and attractive. In this sense, Beck has produced a volume which will be of wide relevance to many aspects of chemistry. Certainly, the author's continual emphasis on the manifold variety of species which can be formed in solution is a refreshing change from the classical treatises on coordination chemistry. The relevance of equilibrium studies to the understanding of kinetics is continually pointed out, and this is useful. Perhaps the greatest shortcoming of the book stems from the same source as its strength: The author, in his enthusiasm for the coordination chemist's view of solutions, has cast everything he sees into the mold of a central metal ion surrounded by a small integral number of strongly coordinated ligands. He has not made it clear that species in solution can never have the degree of "reality" that single molecules in the gas phase or units in a crystal can have. Solution species are a conceptual abstraction of some of the stronger interactions, but their "reality" depends on the method used to "observe" them. There is no contradiction in this, but there may be considerable confusion if this point is not recognized. Thus, Beck's explanations of interactions with the solvent, and of the distinction between infinite dilution and a constant ionic medium as a thermodynamic standard state, tend to be somewhat ambiguous, and will probably mystify rather than clarify these points. In
