No serious errors were noted but (p. 283) the reader should realize that graphite is taken as the stable form of solid carbon for physical, not conuentional, reasons a t 25°C and 1 atm. Clearly this book can serve as the beginning of any student's study of thermodynamics. I t is hard t,o say where it might fit into the usual chemistry curriculum. Possibly-its best place would be as a supplement to certain recent physical chemistry texts (if anyone is using them) which are particularly cavalier in their treatment of thermodynsmics.
The Elerlron-Repulsion Theory of the Chemical Bond
William Fay Luder, Nartheast,ern University, Boston, Massachusetts. Reinhold Publishing Corporabion (a sobsidisry of Chapman-lleinhold, Inc.), New York, 1967. xii 108 pp. Figs. and tables. 1.5 X 23 cm. 83.50, paperbound.
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EDITOR'SNOTE: I t is not 0111 practice to publish two sets of comments ahout one book. We have deviated from that policy because of the nature of the criticism presented by our chosen reviewer (Professor Maneh, whose review starts in the left-hand column below). We feel that he has justifiably indicated where Professor Luder has been a t variance with the fundamental concepts of quantum mechanics. Professor Luder claims thst Professor blanch's statements reflect a biased view. Rather than open bhese columns to pmtracled debate on opinions and attendant semantic problems, we offered Professor Luder the opport,unity of having commenta prepared by a reviewer of his own choice. profess^^ Krohn's remarks therefore accumpany those by Professor bIanch and start in the rightCHARLES E . HECHT hand column below. Both authors have agreed to suggested editorial modifimtions. Hunter College of the BFK City University of Ncw York I n the refa ace of his book. Professor According to the author the material New York Luder says that it is based u p i n the ideas presented in this book is an extension of of J. W. Linnet,t's book "The Electronic the Linnett method of predicting chemical The Structure and Function of Enzymes Structure of Molecules" (Wiley, 1964). structure. The book begins with a disSidney A . Bernhard, University of OreHe then continues: "As stated in my recussion of quantum theory, followed by a gon. W. A. Benjamin, Inc., New York, view of the book (J. CHEM. EDUC., chapter on the structure of atom% "New 324 pp. Figs. and tahles. 1968. xi 43, 55 (1966)), I believe it to be one of the models in atomic structure" are presented 14 X 21.5 cm. Clothbound, $10; pamost important ever published in the field in Chapter 3, along with some Linnett perbound, $4.95. of chemistry." Now Professor Luder has structures. The remainder of the book written astimulatinglittle book of his awn. deals primarily with the Linnett method, This hook is designed to provide s n up One feature of this book is its combinabut s. new twist has been added. to date wrvey of structural enzymology. Upon reading this book one gets the tion of Linnett's approach with that of As such, the hook spans enzyme structure impression t h s t the author is scolding us It. J. Gillespie to extend their illuminafrom basic principles to the latest three for thinking about such things as radial tion of the chemioal bond. However, dimensional structures obtained from and angular nodes, hybrids, resonance, Luder makes clear his disagreement with X-ray crystallography and spans enzyme and electron pair bonds. When we are both Linnet,t and Gillespie on several matmechanisms from traditional cofactoral told that the ". . .illustrations (of the ters. The outstanding example of this mechanism to the latest theories an active angular distribution functions) imply a disagreement is his contention that, in t,he sites of enzymes. I n short, this book prorigidity in the location of electrons in light of eleetron-repulsion theory, the vides a rather thorough and modern view atoms. ." we begin to wonder if we are bhree principal arguments for t,he hypotheof enaymology. reading what we think we are reading. sis of resonance hybrids ("resonance enI n general, the author stresses the chemAs stated in the preface, one reason ergy," the desire to preserve the octet ical approaches utilized to obtain the safar the book is to p r a e n t ". . .new models rule, and the exaggeration of the imporphistication of current day ensymolagy. "A second rea- tance of the eleetron-pair bond) are no of atomic structure.. Thus, the text covers recent aspects of son for the book is to show how the most longer valid. Therefore, he advocates rapid rate kinetic studies with enzymes, serious weakness of the valence theory. . . abandoning the concept. general and specific reaction mechanisms, Probably the most important feature (resonance hybrids). . can be eliminated eto., as well as the more traditional chemof the book is his proposal of new atom from chemistry." ical approaches to enayme structure. L i t The basis for Luder's new models is models: I n these models, atoms are pictle effort is made to relate these well covtured as built up in a. regular way so that presented in the first two paragraphs of ered points with more biological considerathe valence shells of outer electrons are section 3.1 (p. 39). The following is a tions. For example, the concept of allosummary of the major errors and mis- analogous for all three classes of elements: steric enzymes is considered in a limited conceptions contained in these two para- t,he representative elements, the related structural sense without any attempt to graphs. One of the postulates set down metals, and the similar metals. I n stoms correlate the concept with related advanby Luder to develop his models is in- of the representative elements the psttern tages t o either specific or general mmetabolie correct; the Pauli Exclusion Principle is of valence electrons is t,he arrangement of pathways. incorrectly explained; the Principle is the eights and o electrons in t,wo suin-sets I n practice, this book will probably :,I the, w ~ t c r .c ~r I W , ~ t > t w p ~ ~ ~ w r t i i t > g confused with IIund's Rule; and Hund's prove most useful as a supplemental or . gp i ,: I I St I . 111 Knle is backwards. survey text for use by lecturers involved the 11.1110.11 01 To develop his "new models" Luder u t c III- o f 1l.e rcl.t~t!tlIIWI.IIin courses. The text is well documented . t h e valence electrons in valence electrons is t,he arrangement of the states that with review references. The individual an atam arrange themselves around the 12 s a n d d electrons in two spin-sebs a t the chapters provide interesting insights into kernel of that atom according t o . . ." corners of two interpenetrating pentagonal areas often missed by general texts in biothree postulat,es concerning eleot,ron re- pyramids, as in t,he Z n atom. In atoms of chemistry. The book is of less value as a pulsion. The second postulate is: "Be- the similar met,als the pattern of valence direct text for students for it,s scope is cause of their magnetic interaction, a t a electrons is the arrangement of the 16 s somewhat limited and its coverage is often given separation two electrons of op- a n d f electrons in two spin-sets a t t,he in too great a depth. For example, the posite spin have less repulsion for each corners of two interpenetrating heptagonal chapter on enayme kinetics covers such other than do two electrons of the same pyramids, as in lhe Yb atom. sophisticated examples that students readTo arrive a t these models, t,he first step spin." This postulate is taken to be an ing this chapter have difficulty with the explanation of the Pauli Exclusion Prin- is to use three "preliminary postulates" basic principles of the subject. ciple. I t is not. an explanat,ion of the about the nature of electron-repulsion to I n summary, this book serves a useful Principle because it is simply not true. arrive a t the patt,ern models of Ne, Zn, purpose in providing a concise source of I t is not true because i t is contrary to the and Yh. The second step is to apply information about modern chemical enzyobservations generalized in IIund's 12ule. Hund's rule in reverse to the three psttern mology. Undoubtedly, many educators The ground stat,e configuration of free models. For example, first tho cube of and scientists will wish to obtain this book gaseous atoms is the state of maximum interpenetrating spin-sets is justified for to aid their general backgrounds in hiamultiplicity. Luder's postulate would the Ne atom. Second, Hund's role is apchemistry and chemistry. lead one to expect t,hat the state of min- plied in reverse, removing three p electnnrs imum multiplicity would be the ground of the same spin one at a. time, to ohtain JOHN M. CLARK,JR. the models for the F, 0, w d N atoms. state. Hund's Rule may be understood Uniuersily of Illinois (Cmlinued on p. A114, Col. 2 ) Urbana, Illinois (Continued cm page A114, Col. 1 )
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book reviews (Conlinued jrmn p. 126, Col. 2 ) only if there is a certain stability connected with unpaired spins. The fact that the state of maximunr multiplicity is the ground state is not a result of an unusual type of force between the electrons e a magnetic interaction); it is a consequence of the form required of the wave function by the Pauli Exclusion Principle. The Principle states that no two electrons in an atom can have the same space and spin coordinates (the same quantum numbers) or alternatively that the wave function representing two electrons with the same coordinates of space and spin vanishes. This means that the value of the function for such a configuration is zero, and the probability of finding such a configuration is zero. Therefore, the implication in the postulate that Coulomb's Law be repealed is unnecessary. Coulomb's Law may be kept, and the repulsive forces between two electrons considered to vary inversely with r regardless of spin. The paint is that two electrons of opposite spin can be in the same region of space while two electrons of the same spin tend to avoid the same region of space. The occupancy of the same space results in a greater repulsion between electrons of opposite spin than between electrons of the same spin. Thus a. singlet state has a higher energy than a triplet state. Spin correlation (the name given to the tendency of two electrons of the same spin to avoid the same region of space) is required by the Pauli Exclusion Principle; it is not an explanation of the Principle. The correct interpretation of spin carrelation leads naturally to Hund's Rule. This is apparent from the probability distribution plots of the singlet and triplet states in Linnett's book (page 14, 15). I n his treatment Luder implies that the reason two electrons of the same spin do not oceunv the same orbital is a. matter of e w r y ~ r i r . T i is 1 I . The I'auli I'rilwiplr crnrw lllnt n wrlnili i,ehaviw vannot be d w r v c d , not t l . ~ tit i i iu~likd~., on energetic grounds. I n section 3.2, Luder suggests that we limit the application of wave mechanics to one valence electron atoms and that the electron repulsion theory be applied to all other atoms. This suggestion is followed by (on page 48): "One valence electron by itself in an atom seems to display some characteristics of waves. But the difficulties of the wave concept increase enormously when it is applied to two or more electrons in an stom. A tentative conclusion might be as fallows. First, the less reqtricbed the motion of electrons the more evident is their wave nature; the mare restricted their motion the more evident is their particle nature. Second, the larger the number of electrons in the valence shell of an atom, whether isolated or in a molecule, the more restricted is their motion and the more they behave as particles. As a matter of convenience, for the time being, the sssumption will be made that in an isolated 'one electron atom' the wave nature of the electron predominates over its particle nature, and that in an atom with two or
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more electrons the particle nature of the electrons predominates over their wave nature." Thus we are led to s. particle model of the atom. The ptlrticle model of the atom is no more attractive now than it ever was. I t cannot explain quantized energies or quantized angdsr momentum. I t has not been successfully used in any quantitative argument. Neither the Linnett nor the Gillespie-Nyhalm method is based on a psrticle electron. Electron distribution in space is essential to the Gillespie-Nyholm argument and Linnett talks of alternative methods of constructing wave functions. Since this hook and the Luder articles were published, a t least two articles describing the construction of models to represent Linnett structures have apThese are of peared in THIS JOURNAL. some value in teaching the Linnett method but they have the inherent disadvantages of most models. The limitations are particularly disadvantageous with this method because they imply a rigid particle model of molecular and atomic structure. From this point of view this method has heen harmful because it oppeam to he based on the particle electron. I t is not, and we look to Linnett as an authority to determine what he is attempting to do. The following is taken from page 60 of Linnett's book: "In effect the hypothesis presented in this book involves a modification, or extension, of the bssic way of construct,ing the first approximation wave functions for molecules and ions." Originators of new ideas are frequently disappointed with tho way their views are interpreted or put into practice. I t is tho opinion of this reviewer that Luder's book does a great disservice to Linnett and his method.
This paper included caleulatmns using Coulomh's law and the corresponding equation for the force between magnetic dipoles claiming to show that a t small enough distances electrons of the same spin repel each other much more than do electrons of opposite spin. Professor Luder's experience in both teaching and writing are evident in this book. Although some may disagree with his conclosions, all must agree that his treatment of these proposals is attractive and lucid. The electron-repulsion theory is still incomplete and doubtless will he refined and extended in the years to come. Meanwhile, this book should help teachers and students to an inoreased understanding of some of the perplexing problems of the chemical bond and should encourage now thoughts about proposing solutions to these problems.
Toledo, Ohio Concepts in Biochemistry Francis J . Reilhel, University of Oregon, Eugene. McGrsw-Hill Book Co., New 414 pp. Figs. and York 1967. xiii tables. 17 X 24.5 cm. $9.50.
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A short comprehensive text with emphasis on concepts rather than on a.large number of facts is very welcome. As the author says in his introductory chapter, this book is an attempt to present "what I believe to be worth discussing a t this time," hut in fact it covers all the major fields of biochemistry which have eontrihuted so much to the understanding of biological processes within the past ten years. I t is to Reithel's credit that his hook does not start with the usual deseripWALTERA. MANCH tion of chemical compounds (carbohyMonlana Slate University drates, lipids, proteins and minerals), but, Bozaan, 59715 after the short introduction, starts with the basis of enzymatic activity, followed by two chapters on mitochondria1 enzymes. Further chapters are devoted to glyeolysis, (Conlinued jm p. 126, Col. 3) the pentase shunt, photosynthesis, nitrogen fixation, and transport of sugars and When Professor Luder's book was puh- lipids. Five chapters discuss the animo lished in December, 1967, some aspects of acid metabolism, and four chapters discuss t,hese models seemed to conflict with wave- nucleic acids (including synthesis of pumechanics. Since then, relevant details of rines and pyrimidines). The fallowing "standard" wave-mechsnies have been chapters describe protein metabolism, questioned in two papers by it. E . Powell phospholipids, light-sensitive pigments, (J. CHEM. EDUC.,45, 45 and 558 metalloporyphyrins (iron metabolism, (1968)). I n the second of these papers heme complexes, including cytochromes), Professor Powell shows that the nodes and the biosynthesis of co-factors (flavins, obtained from the Scbrodinger approxima- pteridines, coenzyme A and others). The tion do not exist in the relat,ivist.ic wave- last two chapters me on cell membranes mechanics of Dirac. More directly rele- and cell walls and on metabolic networks vant is Professor Powell's proposal of new and their control mechanisms. In an ways of constructing atomic orbitals. appendix, the author gives s. catalog of These are exactly what a t r e required to enzymes referred t,o in his book and arsupport Professor Luder's atom models. ranged strictly according to recommendaI n its discussion of the Paoli exclusion tion of the Commission on Enzymes of the principle, the book disagrees wibh that IUB; this appendix is extremely clear and form of the principle which implies a he- well done and contains, besides the systelief that the principle itself causes electrons matic name and recommended trivial to behave in a certain way. Doctor name, the reaction and appropriate notes Luder's position is that the behavior of covering the specificity and unusual charelectrons is determined by their awn phy- acteristics of the given enzyme. A short sical properties: their negative charges comprehensive list of pertinent literature and their magnetic moments. At the follows each chapter. September, 1968, meeting of the ACS he (Conlinued n page A118) presented a. paper t,o support his position.
