The importance of antibonding orbitals (Orchin, Milton; Jaffe, H. H.)

although care must he taken that it be introduced a t a time when their .... others it now comprises the bulk of the ... theory, hear equations, and s...
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The book is well indexed and abundantly and clearly illustrated. An attractive extra feature is the inclusion of thumbnail biographies. There are, of course, oocasional faults of oversimplification. In a book otherwise so admirably done it is surprising and disappointing that the description and diagrams of orbital shapes (page 6) should be so definitely wrong. The order of orbital energies, 4s < 3d (pp. 6, 38) is not so for the transition metals. The correct order of orbital energies in Nnis 3~~< In,, not the reverse RICHARD W. FESSENDEN as apparently indicated by experimental M e l h Instilute and evidence, which reflects the observable Cmegie-Mella University state of the molecule rather then the best Pitlaburgh, Penmyluania (i.e., HartreeFook) orbitd approximation. Clearly enough, however, disorepancies like these do not significantly interfere with the main thrust of the book. The Importance of Antibonding Orbitals The style is excellent and the content is carefully selected to provide a clear, unM i U a O~chinand H . H . Jaffd, Unicluttered line of thought. Not only is the versity of Cmcinnsti, Ohio. Houghhook well suited to the typical sophomore ton M a i n Co., Boston, 1967. viii organic student, but upperclass under104 pp. Figs. and tables. 15 X graduates, teachers, and in fact most 23 cm. Paperbound. 52.50. others, will also find it an enjoyable reThis sophomore supplement is intended view if not nn introduction to some newer to acquaint the student with the major topics. features and applications of molecular IRWINCOHEN orbital theory, especially in its interpretaYoungatmm State University tions of chemioal structure, infrared and Youngstown, Ohw ultraviolet speotroscopy, photochemistry and the excited state, and electroeyclic reactions. This is s. large order for a 100page book hut it is well done. lntr~dvctionto Quantum Theory The first of the five chapters reviews basic principles and develops the concept Hadrilc F. Hnmeka, University of of bonding and antihonding orbit&. Pennsylvrtnia, Philadelphia. Harper The second chapter defines orthogonality 276 and Row, New York, 1967. x and normalizrttion. (Mathematical a p pp. Figs. and tables. 16.5 X 24 em. paratus and physics1 interpretation are $12. presented with integrations only formally There are, my colleagues inform me, as indicated; no calculations are carried out.) The LCAO MO picture of some firstmany ways of teaching quantum ehemistry to undergraduates as there are row diatomic molecules is then presented quantum chemists. Thii is, I believe, in sufficient detail to add much to the because we have as yet no tradition of students' understanding of hybridization teaching it at this level, and have deand energy level diagrams and to prepare veloped no set patterns. Indeed, there for the succeedimg chapters. is still little agreement as to where the Chapter three is concerned with transisubject belongs in the undergraduate tion metals and infrared spectroscopy. curriculum: at some schools, quantum The structures of transition metal carchemistry per se is not taught at all, s t bonyl complexes are interpreted in terms others it now comprises the bulk of the of d-hybrid sigma bonding with lone pairs second semester of junior year physical of the ligand, together with dw-p back chemistry. bonding with antihonding orbitals of the The disagreement over if and when to CO. With these structures in hand the teach quantum ohemistry is a product of authors proceed to the principles of vibraour uncertainty as to what the subject t,ionel spectra. Force constants, stretching should comprise. One is tempted, on the frequencies, and bond lengths for the one hand, to teach the more practical and carhonyl complexes are correlated with intuitively reasonable aspects of the structures. The unified picture that theory, stressing valence concepts and emerges provides a highly satisfactory the "nature" of ehemied bonding. Such introduction to some relatively sophistian approach must necessarily slight the cated problems. more fundamental theoretical material. Chapter four similarly tzkes up the carA middle approach is to survey rather bonyl group and its ultraviolet transitions, briefly both the theory and applications including singlet and triplet states and an of quantum mechanics, starting with the introduction to excited state chemistry. Schrodinger equation and covering, for Chapter five includes a fine treatment of example, elementary molecular spectrosthe Hoffman-Woadward rules for elecoopy, some valence theory, and nuclear troeyclic reactions, capped with a, chdmagnetic resonance. On the other hand, lenging discussion of symmetry carrelsone may also he tempted to spend the tions. These last three chapters are both entire course dieussing the postulates of solid enough m d elementary enough to do quantum mechanics, the Schrodinger more than merely teach their contents; equation, and the physical interpretations they will in most cases stimulate red of simple problems, without arriving s t interest in both theory and its applicaany "useful" chemistry. Such sn aptions. although care must he taken that it be introduced a t a time when their background is adequate. An equally important use will be by thme not primarily concerned with magnetic resonance hut who must, nevertheless, interpret results from such experiments. After a reading of this book such a person would be familiar with most of the important applications and would be in a. good position to approach more detailed works. This book should be available to all persons in these categories.

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proach is not likely to meet favor with those of us who are not chemical physicists, but it is, nevertheless, the approach of Professor Hameka's new text. The book is "designed to teach elementary quantummeohanics to undergraduates in chemistry and physics." As such, it is more likely to find favor with physicists than chemists, and would he best suited to an undergraduate course in ehemiosl physics-if we have yet reached that stage of early specialization. The major virtue of this text is that it is extrsordinarily self-contained. All the necessary mathematics (except calculus!) has been included: vectors, matrices, Fourier analysis, differential equations, determinant theory, h e a r equations, and so forth. Similarly, a sufficient discussion of classical mechanics is provided, and the historied development of the need for s quantum theory is more than adequate. The initial approach to quantum mechanics is through wave theory and the superposition principle, rather than through the development of eigenvalue equations. Thus, for example, timedependent problems are discussed at unusual length for a text at this level. Siila.rly, the wave functions for unbound states are considered in some detail. The timeindependent Schrodinger equation is not considered until quarter-way through the book, and the hydrogen atom not until near the end. The helium atom is the most "chemical" system considered, and although spin-orbit coupling is briefly mentioned, the L-8 coupling scheme for many-electron atoms is not. Perturbation theory is covered at some length, and the discussion of the variation theorem includes lower bounds as well as upper. However, considering that the (upper bound) variation theorem is of such importance to quantnm chemistry that "in reading some hooks on molecular orbital caloulations, one gets the impression that it has almost replaced the Schrtk dinger equation as the basic equation of quantum theory," little space is devoted to its application except for a. brief discussion of the Hartree-Fock equations and the above-mentioned treatment of the helium atom. Furthermore, the only "practioal" application of perturbation theory is a treatment of the harmonic oseillrttor in an electric field. Chemists may well consider Hameks's selection of topics unusual for a first course in quantum mechanics-at least for a coursein chemistry. Yet thestudent who masters the material in this book will have gained an unusually thorough theoretical background in quantum mechanics. The contents have been chosen to cover all the fundamentally important theoretical methods used in modern qnantum mechanics. The question is one of motivation: students are unlikely to be able to tsckle a full course of unadulterated theory without a more substantial spicing of current (and possible future) appliosr tions. The text is well-produced, with few typographical errors, clearly set equations, and a good index. The writing is clear dthough the approach is sometimes dull. The book can be recommended without reservation to the bighly-motivated

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