Mixed valency is one of various names used to describe compounds which contain ions of the same element in two different formal states of oxidation. The existence of mixed valency systems goes far back into the geological evolutionary history of the earth and other planets, while a plethora of mixed valency minerals has attracted attention since antiquity. Indeed, control of the oxidation states of Fe in its oxides (FeO, Fe304' Fe203) was elegantly used in vase painting by the ancient Greeks to produce the characteristic black and red Attic ceramics (Z. Goffer, "Archaeological Chemistry", Wiley, New York, 1980). It was, however, only 25 years ago that two reviews of mixed valency appeared in the literature almost simultaneously, signalling the first attempt to treat mixed valency systems as a separate class of compounds whose properties can be correlated with the molecular and the electronic structure of their members. Then mixed valency phenomena attracted the interest of disparate classes of scientists, ranging from synthetic chemists to solid state physicists and from biologists to geologists. This activity culminated with the NATO ASI meeting in Oxford in 1979. The 1980's saw again a continuing upsurge of interest in mixed valency. Its presence is a necessary factor in the search for highly conducting materials, including molecular metals and superconductors. The highly celebrated high T c ceramic superconducting oxides are indeed mixed valency compounds.

Mixed-Valence Systems Comprehensive overview on the advanced development of mixed-valence chemistry Mixed-Valence Systems: Fundamentals, Synthesis, Electron Transfer, and Applications covers all topics related to the theory and experimental results of mixed-valence systems, including the design, synthesis, and applications of mixed-valence compounds containing inorganic, organometallic and organic redox-active centers. The text also covers the recent advances in mixed-valence chemistry, including the development of new mixed-valence systems, transition of mixed valency, better understanding of the spectral characteristics of intervalence charge transfer, and controllable electron transfer related to molecular electronics. In Mixed-Valence Systems, readers can expect to find detailed information on sample topics such as: Characterization and evaluation of mixed-valence systems, electron paramagnetic resonance spectroscopy, and electrochemical methods Optical analysis, important issues in mixed-valence chemistry, transition of mixed valency from localized to delocalized, and solvent control of electron transfer Theoretical background, potential energy surfaces from classical two-state model, and quantum description of the potential energy surfaces Reorganization energies, electronic coupling matrix element and the transition moments, generalized Mulliken–Hush theory, and analysis of the band shape of intervalence charge transfer Strengthening the relationship of mixed-valence electron transfer and molecular electronics, Mixed-Valence Systems is of immense value to researchers and professionals working in the field of electron transfer, molecular electronics, and optoelectronics.

Advances in Inorganic Chemistry presents timely and informative summaries of the current progress in a variety of subject areas within inorganic chemistry ranging from bio-inorganic to solid state studies. Thisacclaimed serial features reviews written by experts in the area and is an indispensable reference to advanced researchers. Each volume of Advances in Inorganic Chemistry contains an index, and each chapter is fully referenced.

Mössbauer Spectroscopy Unique and comprehensive overview of versatile applications of Mössbauer spectroscopy in chemistry and material sciences Mössbauer Spectroscopy provides a comprehensive overview of relevant applications of this physical analysis method in chemistry and material sciences. The book shows the versatility of Mössbauer spectroscopy in finding useful information on electronic structure, structural insights, and solid-state effects of chemical systems. A wide range of chemical applications and applied concepts are covered as well as numerous examples, selected from recent literature. To aid in reader comprehension and accessibility, contents are well-structured and divided in different sections covering energy, catalysis, coordination chemistry, spin crossover, sensing, photomagnetism. Edited by prominent scientists in the field and authored by a group of international experts, Mössbauer Spectroscopy covers sample topics such as: Li-ion batteries, catalysts, fuel cells, Fe based silicides and iron phosphates containing minerals Gold clusters and gold mixed valence complexes Molecule based magnets, photoswitchable spin crossover coordination polymers and molecular sensors for meat freshness control With comprehensive coverage of the developments in the technique, Mössbauer Spectroscopy is a beneficial resource for researchers, professionals, and academics in chemistry related fields, such as material science, sustainable environment, and molecular electronics. It can be used by newcomers as well as for educational purposes at the master and PhD levels.

The second edition of this classic book provides an updated look at crystal field theory and its applications.

Molecular magnetism is a new field of research dealing with the synthesis and study of the physical properties of molecular assemblies involving open-shell units. It is essentially interdisciplinary, joining together organic, organometallic and inorganic chemists, as well as theoreticians, physicists and materials scientists. At the core of research into molecular magnetism lie design and synthesis of new molecular assemblies exhibiting bulk properties such as long-range magnetic ordering or bistability with an hysteresis effect, which confers a memory effect on the system. In such terms, magnetism may be considered a supramolecular function. The first eight contributions to this volume present the state of the art in organic supramolecular chemistry, emphasising interlocked systems and molecular trees. The following six articles are devoted to molecular materials constructed from organic radicals and transition metal units. Molecular bistability is then focused on, followed by metal-organic and coordination magnetic materials. A new approach to nano-sized particles closes the work.

Electrochemistry affects several relevant research subjects of physics, chemistry and biology such as the transformation of materials, the transfer of information (especially in living systems), or the conversion and storage of energy. In addition, electrochemical processes constitute a major class of chemical reactions both in the laboratory and on large industrial scales. While conventional analytical electrochemistry provides excellent methods to determine concentrations (e.g. in sensor technology), to yield energy data in the form of redox potentials and to elucidate formal reaction mechanisms via kinetic analysis, these techniques alone are often not immediately suitable to identify unknown species which are formed as intermediates or as products in a redox reaction. The combination of reaction-oriented electrochemistry with species-focussed spectroscopy in spectroelectrochemistry can solve this problem and thus allow for a more complete analysis of electron transfer processes and complex redox reactions. Many research groups from various sub-fields of the chemical sciences have engaged in recent years in using and developing this combined methodology. While the technique has been well developed during the last few decades, its application in various fields of chemistry has only recently become more widespread. Readily accessible, inexpensive equipment and lower barriers to application have contributed to this situation and, at the same time, it is becoming less and less acceptable in chemical research to assign redox transformations without spectral evidence. Spectroelectrochemistry has therefore evolved as a powerful yet usually inexpensive technique which yields mechanistic (chemistry), energy-relevant (electro) as well as electronic structure information (spectro). The whole range of the electromagnetic spectrum can be employed from x-ray absorption to NMR spectroscopies. Yet while the method has become more commonplace, there are still aspects to be considered which require sound knowledge and experience. This book serves as a guide and as an illustration of the kind of research where spectroelectrochemistry can make a difference in the understanding of redox reactions through identification of their intermediates and products. Relevant examples involving UV-VIS-NIR and IR absorption spectroscopy as well as electron paramagnetic resonance (EPR) are presented in this book with the objective to illustrate the potential and the applications of this technique and to provide practical information. The topics covered include: " organometallics " coordination compounds (mixed-valent complexes, metalloporphyrins) " compounds of biochemical interest such as iron-containing proteins The breadth and variety of reactions and materials covered are complemented by the straightforward interpretation of results in the understanding of redox reactions. The solutions available from the spectroelectrochemical investigation in the book do not only provide simultaneous reaction analysis and species identification but also an assessment of electronic situations and of intra- and intermolecular electron transfer. The book aims to familiarise the scientific community with this method by describing the experimental approaches possible and by pointing out under what diverse circumstances this technique can be useful. This book is essential reading for experts and newcomers alike to acquaint themselves with this simple, inexpensive, yet powerful method and it will also appeal to scientists from all chemical sub-fields who have a basic understanding and experience in electrochemistry.

This volume provides a record of the second ASI on the subject "Chemical Physics of Intercalation", which was patterned after its highly successful July 1987 predecessor. A growing community of chemists, physicists and materials scientists has come to appreciate the utility of extending the intercalation concept to generic guest-host compounds and solid solutions. The unifying themes are the complex phase equilibria which result from the competition between repulsive and attractive interactions between and within the guest and host substructures, the tunability of properties by control of guest concentration and superlattice periodicity, and the broad spectrum of potential applications which these materials may provide. The success of this initiative may be judged by noting the enlarged scope of materials covered in this volume as compared to its predecessor. The present volume covers the spectrum from 3-dimensional oxides, 2-dimensional classical layer intercalates,- dimensional doped polymers and zero-dimensional doped fullerene lattices. Hybrid systems such as polymers in layer hosts and nonporous hosts are also treated. Several chapters provide global unifying viewpoints by focussing on sold state chemical aspects, transport and optical properties, the occurrence of superconductivity, etc.

This book provides an up-to-date overview of the Mössbauer effect in physics, chemistry, electrochemistry, catalysis, biology, medicine, geology, mineralogy, archaeology and materials science. Coverage details the most recent developments of the technique especially in the fields of nanoparticles, thin films, surfaces, interfaces, magnetism, experimentation, theory, medical and industrial applications and Mars exploration.

Molecular Magnetism: From Molecular Assemblies to the Devices reviews the state of the art in the area. It is organized in two parts, the first of which introduces the basic concepts, theories and physical techniques required for the investigation of the magnetic molecular materials, comparing them with those used in the study of classical magnetic materials. Here the reader will find: (i) a detailed discussion of the electronic processes involved in the magnetic interaction mechanisms of molecular systems, including electron delocalization and spin polarization effects; (ii) a presentation of the available theoretical models based on spin and Hubbard Hamiltonians; and (iii) a description of the specific physical investigative techniques used to characterize the materials. The second part presents the different classes of existing magnetic molecular materials, focusing on the possible synthetic strategies developed to date to assemble the molecular building blocks ranging from purely organic to inorganic materials, as well as on their physical properties and potential applications. These materials comprise inorganic and organic ferro- and ferrimagnets, high nuclearity organic molecules and magnetic and metallic clusters, spin crossover systems, charge transfer salts (including fulleride salts and organic conductors and superconductors), and organized soft media (magnetic liquid crystals and Langmuir-Blodgett films).