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Book Review Structure Made Crystal Clear Structure Correlation. Vols. 1 and 2. Edited by H.-B. Brgi and J. D. Dunitz

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BOOKS
Structure Made Crystal Clear
Structure Correlation. Vols. 1 and 2.
Edited by H.-B. Biirgi and J. D.
Dunitz. VCH Verlagsgesellschaft,
Weinheim, 1994; 888 pp., hardcover,
DM 398.00.--ISBN 3-527-29042-7
In less than 100 years, our concept of a
chemical substance has reversed from the
thermodynamicist view of a statistical
ensemble of independent entities with internal energies unrelated to the peculiarities of molecular structure, to the stereochemical/quantum chemical picture of a
structurally definable chemical (molecular) entity with a specific relationship between molecular geometry and internal
energy. Indeed, as strongly the chemist of
today would cling as strongly to a CPK
model or ORTEP diagram for reassurance that his chemical intuition was still
valid, as Mach in 1880 rejected the consideration that modeling molecular structure
could give rise to any chemical insight.
This peculiar change in philosophy was
made technologically possible by Bragg at
the turn of the century; it was conceptually founded by Pauling’s (the grandfather
of structure-correlation) expose on “The
Nature of the Chemical Bond”; and, it
was finally embossed on the chemist’s
“tabula rasa” by high gloss and sumptuously seductive images provided by modern computer generated molecular graphics. The structural molecular hypothesis
has been so successful that it is now taken
for granted by virtually every branch of
natural science.
Since Pauling’s revolutionary work. the
silos for structural data have been filled
relentlessly. The fiduciary structural correlations shown by Pauling with 0.1 % of
the present available data still hold fast. In
the last 20 years, however, the concepts of
‘
This section contains book reviews and a list of’
new books received by the editor Book reviews are
written by invitation from the editor. Suggestions
for books to bc irebiewed and for book reviewers
arc wxlcome. Publishers should send brochures or
(better) books to D r . Illenora Beckmann. Redaktion Aiigeuandtc Chemie, Postfach 101 161.
D-6945 I Weinheiiii. Gerinaiiy. The editor reserves
the right of selecting uhich books will be reviewed.
Uninvited books 1101 chosen for rebiew hill not be
returned
structural correlation have evolved beyond structure-structure correlations, primarily due to the work of Hans-Beat
Biirgi and Jack D . Dunitz, to permit extremely detailed and enlightening studies
on chemical dynamics (Structure-Energy
and Structure-Activity Correlations). The
combined expansion of data-base size and
application of statistical methods has
driven structure correlation theory to
have a major impact on small molecular
chemical physics, solid-state chemistry.
and biochemical mechanism and action.
Much of this work has been dispersed so
widely in the chemical literature as to dilute the fundamental message. The task of
bringing to order the many tiles of this
mosaic is nothing less than gargantuan.
Nonetheless, Biirgi and Dunitz have succeeded in creating a magnificent mural of
molecular structure correlation in their recent two volume set from VCH.
“Structure Correlation’’ by Biirgi and
Dunitz covers the entire field in a didactic,
yet research-motivated style. The four
parts of this two volume set break down
the subject into digestible sections: 1) Basics-the “handyman’s” guide to getting
started in structure correlation; 2) Molecular Structure and Recictivity-demonstration of the principles and the kinds of
chemical intuition that can be derived; 3)
Crpytal Packing--a view separating the
forest from the trees in solid-state chemistry; 4) Proteins and Nucleic Acids-biochemical insight from an ordered look at
biomolecular structure. As a (self) teaching tool, this collection will empower the
structural chemist to tackle the most important problems at the heart of materials
and biomolecular technology. As a reference it will provide researchers from all
facets of molecular science with a compass
to facilitate their structural investigations.
I ) Basics: The first part of the series
contains five well written chapters which,
with some mathematical background (or
fundamental references) will give the
reader the necessary foundations in structure correlation theory. Chapters 1 and 2
cover fundamental quantitative specification of structures and structural distortions. The discussion of coordinate systems and symmetry arguments starts at an
entry level that will be useful in course
work. Chapter 3 provides an excellent
overview of the hows and whys of the various available crystallographic data bases.
Statistical packages accompany several
databases, and Chapter 4 covers many of
the common types of analysis that can be
done with these packages and the significance of these analyses to structural correlation studies. Chapter 5 introduces the
reader to chemical questions that can be
addressed by the structure correlation
method. The concept of the potential energy surface and the physical parameters
that can be derived from knowing this surface are discussed with select chemical examples. As this first part of five chapters is
strongly oriented toward newcomers to
the field, I list here some small typographical errors to alert the reader that it is not
a glitch in their own algebraic manipulations. For example, page 5, the block matrix formula entry for column 3, row 2
should be A,, not
page47, Figure 2.9, the line numbering would be more
consistent if the ends were swapped on the
last four linear projections; page 53,
Table 2.6, the operation R,4,s(xz) in the
left column should be RAB; page 168,
lines 14-15, the sentence should read
“The eigenvector, associated with the
smallest eigenvalue of,f, points in the direction ...”; page 196, line 5. the equation
should read qo = (Drfo DrI,)1’2.These
are trivial matters and in no way detract
from the desirability of the book.
2 ) Molecular Structure arid Rractivitjt :
The second part begins to expand the concepts and applications of structural correlation. The chapter on organic addition
and elimination reactions, by Cieplak, is
an exhaustive and scholarly treatise, but
does not have the same teaching value as
some others. It is a wonderfully detailed
collection of the subtleties of reactions at
trigonal carbon, but one wonders if the
depth and detail are warrented in the
present context. Chapter 7 by Biirgi and
Shklover depicts the classical art of structure-correlation theory. Working from
data on the structural distortions of primarily inorganic compounds, they show
the similarity of reactions based on coordination number rather than atom type.
These early examples established the generality of the methods. The chapter by
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BOOKS
Auf der Heyde on transition metal complexes is very well written and gives the
reader a good perspective how to use
statistical methods to extract order from
(greatly simplified) clusters of data. Cluster analysis and principle coordinate analysis are techniques to which the average
chemist is exposed; however, Auf der
Heyde does an excellent job showing the
usefulness of such methods in studies of
ligand field exchanges and rearrangements. The final chapter of Volume 1 by
Schweizer on conformational analysis is
also a classic in the field. The conformational analysis of polyaryl X compounds
and medium ring systems is one of the
proving grounds for structure correlation
analysis. Schweizer clearly presents these
classic studies.
3) Crysstul Packing: Part 3 comprises
three chapters which really display the
power of structural correlation theory to
elucidate molecular interactions when
linked to a database like that of CCDB.
The chapter by Brown builds directly on
Pauling’s fundamental work; this chapter
demonstrates how elegantly the Pauling’s
bond-lengthlbond-order relationship applies to a wide variety of systems. Indeed,
this is really the basis of the original structural correlation ideas. The following
chapter, by Bernstein, Etter, and Leiserowitz, on hydrogen bonding is one of the
best in the collection. Although I found
their original definition for the existence
of a hydrogen bond to be cyclic (a hydrogen bond exists when there is evidence for
the existence of a bond involving a hydrogen atom) they present a practical scheme
for describing and organizing hydrogen
bonding patterns as well as a number of
useful energetic thumb rules for predicting the hierarchy of hydrogen-bonded
aggregates. This chapter would be improved if standard chemical structural
formula accompanied the many packing
diagrams which contain no atomic or
bonding labels, and it would be nice if
they consistently used their network notation to annotate all of the exemplary figures. Figure 1 1.15 on page 459 has the labels for part a and part b reversed. The
chapter by Gavzzoti describes the substantial advances that have been made
toward the derivation of a consistent force
field for crystal environments. This chapter is perhaps one of the most important
for future developments in computational
crystal engineering. The formulae in the
chapter often used the same capital letters
to mean different things which makes
the reading a little bit cumbersome, but
the ideas are well worth the effort.
Table 12.2 must have some numbers for F
switched or wrong, particularly those for
tetraphenylmethane, adamantane, and
DABCO.
4) Proteins and Nucleic Acids: Part 4
contains a series of chapters on biological
structure, which except for Chapter 13 by
Klebe d o not fully blend into the style of
the book. The chapter on steroids is more
an expose than a lesson. The chapter of
protein structural motifs is not easily accessible to the nonspecialist; this chapter
could have been a jewel with a few more
pages of background, and a conscientious
attempt to define terms and jargon rather
than just citing literature and expecting
the readers to fend themselves. Blundell’s
contribution was for me interesting but of
such small scope that I felt it might well
have been included with a broader discussion. Indeed, a combined chapter containing the principles of Chapters 15, 16, and
17 from a generalist’s perspective would
have been more fitting for the book. Ultimately, although this final section of four
chapters is competent. it reads like an afterthought rather than an integral part of
the structural correlation field.
In summary, I feel all of the contributing authors did a splendid job; however,
the diversity of topics is such that few
readers will remain “riveted” throughout
the whole 18 chapters. Indeed, in this day
of interdisciplinary hype. it is a pleasure
finally to read a book that truly captures
the spirit of boundary-free research. Thus,
I would call “Structure Correlation” by
Burgi and Dunitz a “must have” for anyone interested in molecular structure. My
copy stands on my shelf of most accessed
books.
Jay S. Siege1
Department of Chemistry
University of California-San Diego
La Jolla. CA (USA)
High Resolution NMR in the Solid
State. Fundamentals of CP/MAS. By
E. 0. Stejskal and J. D. Memory. Oxford University Press, Oxford, 1994.
189 pp., hardcover E 30.00.-ISBN
0-19-507380-0
The subject of high-resolution solidstate NMR, including all fundamental
aspects of N M R of solids, has been thoroughly treated in several excellent monographs. However, these books have been
written by physicists in language which is
often not at all familiar to chemists. At the
other extreme, a number of Fairly oversimplified, purely qualitative introductions to solid-state N M R have appeared,
aiming at the chemists’ approach by try-
ing to more or less completely avoid
“unloved” topics such as mathematics
and quantum mechanics. In between these
two extremes there exists a large gap: the
attempt to provide a bridge between these
two worlds is, by its very nature. an extremely difficult task, like trying to square
the circle. The task is so difficult because
there simply is no purely qualitative approach to high-resolution solid-state
N M R which would d o justice to the subject. This difficulty of translating and
communicating between the worlds of
physics and chemistry is almost certainly
the reason why no such “intermediate”
textbooks on CP/MAS N M R have appeared on the otherwise well supplied
N M R book market. On the other hand, a
textbook on CP/MAS N M R at that level
would certainly represent a much needed
commodity, especially since many Fascinating and challenging applications of
high-resolution solid-state N M R methodology in the field of chemistry remain to
be explored. Any serious effort to make
the principles of CP/MAS N M R more
accessible to the chemistry community is
therefore to be welcomed.
The book by Steijskal and Memory represents a quite successful attempt at
squaring the circle. From every page in
this book it is obvious that it has resulted
from long experience of teaching the subject to undergraduate and graduate students. The strategy follows a step-by-step
method, starting with the introduction of
the basic principles of N M R in Chapter 1.
This introduction also includes a brief explanation of the density matrix formalism
which is absolutely necessary. This explanation should certainly provide a golden
bridge for readers more familiar with solution-state N M R ; the example chosen is
the polarization transfer experiment in solution using the DEPT sequence. Naturally, an introduction compressed into approximately ten printed pages can only
outline the general idea, but all important
references for further reading are given.
Chapter 2 is devoted to cross-polarization (CP) in the solid state and follows
“traditional” descriptions within the
framework of a thermodynamic approach, introducing the concept of spin
temperature. For this chapter too all important key references are given in the
bibliography. Although it is implicitly
clear that this approach to explaining C P
under Hartmann-Hahn matching conditions is only valid for a rigid lattice with
an abundant spin reservoir as the source
of magnetization. a more explicit statement about the limitations of the thermodynamic approach would seem necessary.
Also, given the strategy of starting out
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