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Book Review Transition Metal Oxides. An Introduction to their Electronic Structure and Properties. (International Series of Monographs on Chemistry Vol. 27.) By P. A

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down came with the discovery of lignin-peroxidase in 1983,
but the fate of the phenoxy radicals that are formed after the
initial oxidation step is not yet understood. The topic of how
microorganisms interact during degradation raises more
questions than answers. Most investigations are carried out
using pure cultures, but this book shows very clearly that
there are many different isolated strains that can use a given
substrate as a carbon source. In contrast to the understanding of the functions of individual microorganisms, little is
known about the cooperative functioning of several specialized microorganisms, nor about the ecology of the functionally redundant types. The first insights into these questions
are now coming from studies of the degradation of wood in
soil and of cellulose in the digestive systems of ruminants.
However, studies of the “communication” between microorganisms and their metabolic interactions are only just beginning.
The main emphasis of the book is on microorganisms and
their enzymes, whereas there is in general relatively little
theoretical discussion of the chemistry and mechanisms of
degradation. The book is essentially a literature survey and
a work of reference, and the detailed bibliographies citing
material for further reading, as well as an index of microorganisms and enzymes at the end, are consistent with this
purpose. It can be recommended for everyone interested in
studies of microbial degradation, and also especially for
users of such processes.
Bernhard Hailer
BASF AG, Ludwigshafen (FRG)
Transition Metal Oxides. An Introduction to their Electronic
Structure and Properties. (International Series of Monographs on Chemistry, Vol. 27.) By P. A . Cox. Oxford University Press, Oxford, 1992. IX, 284 pp., hardcover
€. 37.50.--ISBN 0-1 9-855570-9
As the author mentions in the preface to this book, interest
in the oxides of the transition metals can be traced far back
into antiquity. These compounds are nowadays of enormous
importance in chemical technology, for example as magnetic
pigments, white pigments, laser materials (e.g., garnets), and
X-ray fluorescent materials (e.g., BaWO,). They are also an
important subject of basic research, which has led to a deeper
understanding of many physical properties of the solid state.
One of the most significant recent discoveries is that of the
new high temperature superconductors (the oxocuprates),
the study of which provides a good illustration of the close
connection between structure and properties in the solid
state.
This book is not so much concerned with describing the
great variety of transition metal oxides as with discussing
their widely varying electronic properties. The first chapter
starts by briefly explaining some basic concepts of solid state
chemistry, such as oxidation levels, nonstoichiometric compounds, the phase rule, and phase diagrams. This is followed
by an equally concise treatment of the coordination of metal
atoms by oxygen, the resulting polyhedral crystal structures,
the occurrence of defects in these, and an overview of electronic properties.
Chapter 2 describes the essential features of various models for interpreting electronic structures, ranging from the
purely ionic picture of the ligand field theory, through the
molecular orbital (MO) theory, to the band structure model.
Intermediate models such as the Hubbard model and the
Anderson localization theory are also discussed. Chapter 3
begins by discussing band gaps in relation to spectroscopic
properties, based on examples of nonconducting oxides of
metals with do, d8, or d ” electronic configurations. The
author then deals with the question of the assignment of
bond energies in doped and undoped transition metal oxides,
and the various types of magnetic interactions that can occur
in these materials. Chapter 4 is concerned with physical effects in semiconducting oxides, such as the properties of the
charge carriers, point defect models, carrier binding energies,
spectroscopic studies of free and bound charge carriers, and
transitions to the metallic state. The fifth and last chapter
deals with band structures and with the transport and optical
properties of metallic transition metal oxides, and ends with
a brief discussion of the new high temperature superconductors and the problems of developing a theoretical understanding of their properties.
A praiseworthy attempt is made in this book to treat the
chemistry of transition metal oxides from the standpoint of
their physical properties. Although the descriptions of the
various theoretical models are brief and sketchy, the understanding of them is helped by numerous tables and diagrams.
However, the reader whose interest in the subject goes beyond a superficial level is not well served. Also anyone who
hopes for an overview of the whole field of transition metal
oxides will be disappointed. Moreover, the treatment of the
subject is incomplete insofar as oxides with localized metalmetal bonds, such as reduced oxomolybdates and oxoniobates, are not covered.
Despite these criticisms, the book can be recommended
for all whose work is concerned with the structure and properties of solids. The many literature references provide an
excellent starting point for more advanced reading in this
area.
Jiivgen Kiihler
Max-Planck-Institut fur Festkorperforschung
Stuttgart (FRG)
Oxygen Chemistry. By D. 7: Sawyer. Oxford University
Press, Oxford, 1991. 223 pp., hardcover .€ 30.00.ISBN 049-505798-8
Within the Interndona1 Series of‘ Monugruphs on Chemistry Donald Sawyer has provided a new book on different
aspects of the chemistry of oxygen. In a one-page preface,
R. J. P. Williams mentions that molecular oxygen is one of
the major constituents of the atmosphere and that life depends on the kinetic barriers to oxygen reactions, in the
presence of a very strong thermodynamic drive. This stimulating book is an attempt to show how the entire chemistry
of oxygen (molecular oxygen and its reduced forms) in
aqueous and non-aqueous media can be treated in a unified
way, leading to a comprehensive understanding of all the
different reaction pathways involving oxygen.
The book is divided intoeight chapters. After an introductory chapter dealing with fundamentals such as the central
role of oxygen in chemistry, and 0, as a unique natural
product, Chapter 2 describes the redox thermodynamics for
oxygen species (ozone, molecular oxygen, HOO.. 0; .,
HOOH, HOO-, 0, O - . and HO-). This chapter contains
useful tables on reduction potentials in aqueous or aprotic
solvents which are generally widely scattered throughout the
literature. The chemical versatility of dioxygen species (oxido-reduction. atom transfer, or dismutation) is mainly influenced by the reaction medium. Chapter 3 describes the nature of the chemical bonds in oxygen species, on the basis of
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