tion of excited molecular energy levels but who also cares about, say, the nature of the complexes of chromium(II1). It is a useful book for the mature scientist who wishes to reconsider some of his preconceptions about what electrons are doing in molecules. However, i t is a difficult book t o read, for Jdrgensen d r s m from far and wide t o nail down his side of eaxh argument. The notation is often forbidding.
L. CARLIN RICKARD B~om University Providence. Rhode Island
Hyperconiugafion Mzehael J. S. Dewor, University of Chicago. Ronald Press Co., Xew York, 184 pp. Figs. and tables. 1962. vi 11.5 X 21 em. $6
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counted as being too small, solvent dependent and possibly caused by several other influences such as steric inhibition of salvation; secondary isotope effect evidence is judged inconclusive since the importance of possible other factors has not been established. A detailed quantitative analysis of reactivit,y effects of substituents suggests that the appment resonance effects of alkyl groups are largely inductoelectromeric in nature although hyperconjugat,ion may be important. Thus in the end hyperconjugation emerges stripped of much of its territory but not quite abolished. Its more powerful ally, conjugation, has incidentally sustained significant losses. One cannot help but wonder how wellsome of the other concepts and explanations, here admitted readily in preference to hyperconjugstion, would hold up if subjected to a similarly devast,atine critical analvsis. Of these effects perhaps inductiv; would survive hut wo11ld inductoelectromeric?
I t is an interesting, stimulating and useful exercise occasionally to re-examine various concepts extremely critically to see how well we can do without them. I n this book, hyperconjugation suffers this test of Theories of Electrons in Molecules fire a t Professor Dewar's capable hands. William T. Simpson, University of The reader receives some warning that Washington, Seattle. Prentiee-Hall, what results is not necessarily a balanced Inc., Englewood Cliffs, New Jersey, view of the problem by the author's pur183 pp. Figs. and 1962. viii pose, stated in the preface, t o "outline the tahles. I fi X 23.5 em. $6.75. present position in a moderately impartial manner." "This book is intended to fill in the gap Professor Dewar adopts the view that i t beheen what is found in quantum chemis a purely arbitrary but nevertheless very istry books and what is found in the useful description t o consider valence journals." Thus, this hook has as a preelectrons in any molecule t o be localized in requisite for its readers, a rather careful definite bonds and that this description perusal of some of the extensive quantum should be preserved so long as it gives an mechanics or quantum chemistrv texts. accurate representation of molecular propThis makes i t a text which will be quite erties. Thus the delocalieation of elecdifficult to read for anyone but the student trons of single bonds (byperconjugetion) of quantum chemistry, and will have a relm l of p or pi elccrrons ~ ~ n i t l ~ . l t i o n )atively limited audience. For this limshould be i n r l d r d 2 s p u t of rhr vlt.crnmic ited audience, it is 8. welcome addition in desc"t,l.iw> w l v i f t l w lomlizmi h w d uic. it,s careful treatment, with great matheture fails. matical elegance, of a number of advanced All of the main lines of evidence which problems in quantum chemistry. The have been used to support hypereonjugaauthor states in the preface that the aim tion are examined and alternative exis more in the direction of rigor than in planations are offered in most cases. Varintuitive understanding. It is surprising, iations of heatsof formation, bondlengths however, after this statement, to find him and dipole moments, which have prefrequently interspersing his mathematical viously been attributed to hyperconjug* elegance with purely intuitive statements. tion, are rationalized in terms of the deThe hraeket notation used is the most pendence of these bond properties on the formal one known to this reviewer; it is hybridization state of carbon. Conjugararely found in journal articles, but, as the tion as well as hyperconjug&m is judged rtuthor points out, is used "because it is a to have a n unimportant influence on these part of the apparatus of transformation properties, "which depend on the collectheory." tive behavior of valence electrons," in The book is organized in four chapters; "classical" molecules such as 1, 3-hutaan introductory chapter on atoms, and diene or propene. separate chapters on the moleculxr orbital Although the evidence for single bond method, the valence band method, and the electron delocalization effects on physical independent systems approach. Thus, properties "which depend on the behavior the book clearly indicates that the choice of individual electrons," e.g., nuclear of topics treated depends not so much on qnadrupole resonance (NQR), nuclear their general interest, but reflects the magnetic resonance (NMR) and electron writer's own special interests. Each spin resouhnce (ESR) spectra, is admitchapter bas its awn appendix. Technitedly conclusive, in Professor Dewar's cally, the book has very high standards; view "evidence of this kind has no bearing i t is well printed and well hound. on the problem of hypercanjugstion in the ohemicsl sense." In considering evidence from chemical reactivity the Baker-Natban effect is dis-
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232 / lournal of Chemical Education
Nouveau Trail& d e Chimie Minirole. Volume 15, part 3, Tranruranienr Paul Pascal, general editor. Masson et Cie., Paris, 1962. 1 1090 pp. Figs. and tables. 17.5 X 26 cm. BrochB, 180NF. Cartonne toile, 192 NF.
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Uranium and uranium compounds were described in the previous parts of this volume, and this part is concerned with the trrtnsurmium elements. I t begins with an excellent introduction to the chemistry of the rsdioelements by H ~ i s sinsky, which includes information about the new elements and their atomic struotnre, radioactive transformations, nuclear reactions, physical and chemical reactions of radiations, measurements, and natural radioelements. A %-page table of radioactive isotopes concludes the introductory material. The treatment is thorough, and the summary will he a valuable addition for reference needs. The remainder of this part of the volume is divided into two sections: the uranides (neptunium, plutonium, and americium) and the curides (eurinm, fermium, mendelevium, nobelium, and the last elements of the periodic system), with additional material on lawrencium, natural rttmospheric radioactivity, artificial atmospheric radioactivity, radioactive fallout, and atmospheric diffusion of fission products. Illustrations, charts, and graphs are used frequently and effectively. Literature references are numerous, and the same arrangement for these as for previous volumes has been followed by which the location of bibliography for each chapter is indicated a t the bottom of each page of text. The third part of the volume has some 1,090 pages of the more than 2,500 devoted to the entire volume. Indexing is by each individual part, and there is no cumulative index for the three. As is the case with the entire set publi~hedto this time, the indexing leaves much to be desired as to thoroughness, although it is adequate for the more general subjects. In general, few criticisms may be made, and the introductory material alone of the third part is a most valuable addition t o the literature sources available to those concerned with nuclear chemistry, a8 well as other areas concerning radioactivity and the transuranium elements. ROGERV. KRUMM University of Florida Gainesuille
Nouveau Tmiti d e Chimie Midrole. Volume 20, Allioges M&tolliquer. Part 1 Paul Pascal, general editor. Masson et 771 pp. Figs. Cie., Paris, 1962. 1 and tables. 17.5 X 26 cm. BrochB, 134 NF. CartonnB toile, 146 NF.
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Volume 20 of the Pascal treatise is to be devoted to alloys, with division into three parts. The index will not appear until completion of part three, as it is intended to indicate there whether any particular alloy consists of a binary or (Cdinued a page AS16)
