Chemical Education Today
Book & Media Reviews Metallocenes Nicholas J. Long. Blackwell Science, Inc.: Malden, MA, 1998. 285 pp. ISBN 0-632-04162-5. $54.95.
Informative, readable, unpretentious. That is how I would describe Nicholas Long’s book if I were asked to do it in just three words. Indeed, the book under review is a straightforward, balanced survey of metallocene chemistry all across the periodic table, written in a textbook format and aimed at advanced undergraduate and graduate students and researchers in the field. Covering from synthetic methodologies and reactivity patterns to structural and bonding aspects of the so-called “sandwich” complexes, it is a candid compendium of a virtually limitless area of organometallic chemistry. It is interesting to note that a more authoritative, two-volume set on metallocenes was published almost simultaneously (Metallocenes; Togni, A.; Halterman, R. L., Eds.; Wiley-VCH: New York, 1998; ISBN 3-527-29539-9; $265.00). However, with the exception of the title and year of publication, the latter is quite different in scope and organization, having a clear emphasis on early transition-metal chemistry and separate chapters written by invited experts. Long’s book is divided into six chapters, starting with Chapter 1 introducing the history and classification of metallocenes. The author clearly states his desire to present an overview of compounds containing only two or more cyclopentadienyl (Cp) ligands, including parallel, bent, main group, and multidecker species. Thus, almost completely excluded from the text are monocyclopentadienyl (halfsandwich) complexes and derivatives with heterocyclic or conjugated ring systems. While this choice is understandable in terms of space, perhaps even justifiable, I regret to find only a marginal treatment of compounds with substituted Cp ligands. It would have been useful, at least for those new to the field, to summarize the distinctive features of bulky Cp ligands, of which the pentamethylcyclopentadienyl (Cp*) is probably the most popular. Furthermore, the application of sterically demanding Cp ligands is one of the most important synthetic strategies that have contributed to the progress of organometallic chemistry in the last couple of decades or so. Chapter 2 reviews the synthesis and physical properties of metallocenes, including derivatives of the alkaline earth, transition, and main group metals, the lanthanides, and the actinides. The conspicuous absence in this chapter of a sec-
1488
tion on metallocenes of the alkali metals is unfortunate given the fascinating structural chemistry they exhibit, as seen recently for the lithocene (LiCp2{), sodocene (NaCp2{), and triple-decker Cs2Cp 3{ anions (Harder, 1994, 1996), whose structures are only hinted at in section 5.1.8 later in the text. Chapter 3 deals with the electronic structure and bonding in metallocenes and includes a lucid discussion of ionicity vs covalency in Cp complexes. Chapter 4 outlines the reactivity and spectroscopic properties of metallocenes, from the extensive organic chemistry of ferrocene to the study of fluxional processes in sandwich compounds. Chapter 5 contains a fairly detailed description of the synthesis, properties, spectroscopy, and structures of bridged metallocenes (i.e., metallocenophanes), followed by shorter sections on polynuclear and multidecker derivatives. The last chapter is perhaps the most interesting, and the author does an excellent job presenting the main uses of metallocenes, from olefin polymerization reactions to the design of new ferromagnetic and nonlinear optical materials. It is also entertaining to learn about some of the applications of metallocenes in medicine, molecular recognition, asymmetric catalysis, and organic synthesis. Each chapter is supplemented with some 20 to 40 selected references, some as recent as 1996–97. The book has been carefully produced and the number of typographical errors (e.g., retardents instead of retardants [p 269]) or inconsistencies (e.g., carbon and its heavier congeners are referred to as group 4 elements in Chapter 3 [p 104] but as belonging to group 14 elsewhere in the text) is minimal. Factual mistakes are even harder to spot, but the structures of the tris(cyclopentadienyl) complexes Cp3Sb and Cp3Bi are known (Lorberth, 1981, 1995), contrary to what is alluded in Chapter 2 (p 76). Notwithstanding these oversights, the book, on balance, is an attractive overview of metallocene chemistry and I gladly recommend it. In addition, I will prefer to buy Long’s book and let the library purchase Togni and Halterman’s related treatise, whose list price is almost five times higher. Whether the reader is a beginner interested in learning basic organometallic chemistry or a professional looking for a handy reference guide on the subject, Long’s text should appease anyone with an appetite for sandwich compounds. Daniel Rabinovich Department of Chemistry The University of North Carolina at Charlotte Charlotte, NC 28223
Journal of Chemical Education • Vol. 76 No. 11 November 1999 • JChemEd.chem.wisc.edu
