bluuebunny/crossref_metadata_2025_split huggingface dataset:
Beryllium & Magnesium: Organometallic ChemistryBased in part on the article Beryllium & Magnesium: Organometallic Chemistry by E. Alexander Hill which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Saulys Dovas A. , Hill E. Alexander 
Published: December 2011

AbstractVictor Grignard found in 1900 that solutions of organomagnesium halides form easily in the reaction of an organic halide with magnesium metal in diethyl ether. These Grignard reagents undergo useful reactions with many kinds of substrates. This discovery ushered in a new era in organometallic chemistry and provided chemists with a powerful and versatile reagent for synthesis of a wide variety of organic and organometallic compounds. This article discusses Grignard reagents in the broader context of organomagnesium chemistry. Preparatory methods surveyed include direct reaction of organic halides with the metal, exchange reactions with other organometallic compounds, as well as carbo‐ and hydrometalations. The current level of understanding of the mechanism of Grignard formation is summarized. The formation and reactivity of unusual species such as cluster Grignard reagents, for example, RMg4X (R = organic group, and X = halide) and polymagnesium compounds, for example, Ru[C5(MgCl)5]2are also discussed. The bonding and structure of organomagnesium compounds (as well as that of beryllium analogues) as described by diffraction methods, thermochemical data, colligative properties, spectroscopic (vibrational, nuclear magnetic, and electronic) measurements, kinetic studies, mass spectrometry, and theoretical methods are outlined.The most prominent chemical property of organomagnesium compounds is their ability to deliver an effectively ‘anionic’ organic group with nucleophilic properties. As alkylating reagents, their important reactions include nucleophilic displacement of less basic leaving groups from saturated carbon atoms or other elements, addition to carbonyl groups and other unsaturated functions, and nucleophilic substitution at the acyl group of carboxylic acid derivatives. This broad array of substrates is surveyed, as are the effects of solvents and catalysts on reactivity. Less conspicuous reactions with wholly or predominantly inorganic substrates are also considered. Electron transfer reactions where organomagnesium compounds act as reductants are discussed.Organoberyllium compounds are more difficult to prepare and are less nucleophilic than their magnesium counterparts. These features, together with their high toxicity, have limited their utility. Methods of preparation, as well as descriptions of bonding, structure, and reactivity patterns are presented. Of special note are recent advances in cyclopentadienyl beryllium chemistry, as well as the advent of beryllium–silicon chemistry.
Cadmium: Organometallic ChemistryBased in part on the article Cadmium: Organometallic Chemistry by Gerard Parkin which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Gupta Niladri Narayan , Atwood David A. 
Published: December 2011

Abstract
As a large, soft, heavy element, the chemistry of cadmium is marked by relatively weak bonding to carbon and other more electronegative atoms. Organocadmium compounds thus demonstrate diverse reaction chemistry. Furthermore, the large size and low valency of cadmium leads to interesting aggregated compounds. The reactivity and structural importance of organocadmium compounds and applications in solid‐state chemistry is offset by their high toxicity.
Carbon: Fullerenes
Authors: Crane Jonathan D. , Kroto Harold W. 
Published: December 2011

Abstract
The discovery of the fullerenes has revolutionalized the chemistry of carbon. For the first time a molecular form of the element carbon is available that can be manipulated and functionalized by the wide range of techniques available to molecular and materials scientists. In a very short space of time the fullerenes and their derivatives have been found to display many fascinating physical and chemical properties, and the astonishing pace of development in fullerene research is ample testimony to their great potential.
Chalcogenides: Solid‐State ChemistryBased in part on the article Chalcogenides: Solid State Chemistry by Patricia M. Keane which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Kanatzidis Mercouri G. 
Published: December 2011

AbstractThis article deals with the solid‐state chemistry of chalcogenides and describes mainly the developments during the past decade. The article is not exhaustive but is meant to give a broad set of examples of interesting compounds and solid‐state chemistry of these compounds so that the reader can obtain a reasonable and rounded view of the recent activities in this area. Further depth and additional information can be obtained from the available references.
Chromium: Biological Relevance
Authors: Vincent John B. 
Published: December 2011

AbstractThe biochemistry of CrIIIhas been a poorly understood field of endeavor; studies of the biochemistry of none of the other transition metals have been as problematic. Despite four decades of investigation, only recently has a clear picture of the role of Cr been defined potentially. The biologically important form is the trivalent ion, although not in the form of the purported glucose tolerance factor. Apparently, CrIIIis required for proper carbohydrate and lipid metabolism in mammals, although Cr deficiency is difficult to achieve. Conditions that increase circulating glucose and insulin concentrations increase urinary chromium output. Cr is excreted after an insulin challenge, probably in the form of the oligopeptide chromodulin. Chromodulin may be the key to understanding the role of Cr at a molecular level as the molecule has been found to bind to the activated insulin receptor, stimulating its kinase activity. A mechanism for the action of chromodulin has been proposed recently. The popular nutritional supplement chromium picolinate has been associated with potentially deleterious effects. The mechanism of toxicity of chromate (CrVI) is still an area of intense investigation.
Chromium: Inorganic & Coordination Chemistry
Authors: Theopold Klaus H. 
Published: December 2011

Abstract

The element chromium (Cr, atomic number 24) belongs to the first row of the transition metals, the properties of which are marked by partial occupation of their 3d orbitals. Together with molybdenum (Mo), tungsten (W), and unstable seaborgium (Sg), it makes up group 6 of the periodic table. Chromium is relatively abundant, occurring naturally in various oxide minerals (notably chromite, FeCr
2
O
4
). Because of its resistance to reaction with air and water, thin coatings of chromium are used to protect other metals against corrosion. Chromium features a great variety of accessible oxidation states; among these the +VI, +III, and +II states are of prime importance. Octahedral coordination compounds of Cr(III) are very stable and numerous; they have played a prominent role in the development of coordination chemistry. Hexavalent chromium is a very strong oxidant. It has traditionally been used in organic synthesis, but the inevitable metal wastes have discouraged its use as a stoichiometric oxidant. Cr(VI) is a known carcinogen, but there are no indications of adverse health effects of Cr(III); the latter is indeed an essential trace mineral implicated in glucose metabolism. Heterogeneous chromium catalysts play an important role in the catalysis of ethylene polymerization.
Cobalt: Inorganic & Coordination ChemistryBased in part on the article Cobalt: Inorganic & Coordination Chemistry by David A. Buckingham which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Blackman Allan G. 
Published: December 2011

AbstractThis article provides a summary of the important and interesting aspects of the inorganic and coordination chemistry of cobalt. A brief history of the element, detailing its discovery and historical uses, is given, and some general information concerning the properties of elemental cobalt is detailed. The general chemistry of cobalt is then outlined, including an overview of the common oxidation states found in inorganic compounds and complexes, a discussion of the stereochemistry, spectra and magnetism of cobalt complexes, and an outline of some analytical methods used for cobalt. The inorganic chemistry of simple cobalt salts is then described, and the coordination chemistry of cobalt, which constitutes the majority of the article, is then outlined in some detail. Coordination complexes of cobalt are detailed according to the oxidation state of the metal ion, with complexes ranging from Co(−I) to Co(V) discussed. Brief descriptions of the chemistry of each oxidation state are given, and specific examples are then outlined according to the nature of the ligand donor atom(s), with extensive references to both the primary literature and to review articles given. Thus, Co(I), Co(0), and Co(−I) complexes containing aliphatic, aromatic, and macrocyclic amine ligands, as well as Schiff‐base, porphyrin, and P‐donor ligands are discussed, while Co(II) complexes of carboxylate, heterocyclic, and oxygen‐derived ligands are summarized. Co(III) ammine and amine complexes are described in detail, while Co(III) complexes containing O‐donor ligands are also discussed. The few known Co(IV) and Co(V) complexes are outlined.
Cobalt: Organometallic ChemistryBased in part on the article Cobalt: Organometallic Chemistry by Ulrich Koelle which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Quisenberry Keith T. , Hanusa Timothy P. 
Published: December 2011

AbstractAmong the longest known families of organometallic compounds, those of cobalt display great diversity in their structures and oxidation states. The ligands accommodated in organocobalt compounds range from strong σ‐donors such as hydrides and alkyls, to π‐acid ligands such as carbonyls and phosphines. The carbonyl cluster compounds of cobalt are numerous and they play a major role in catalytic reactions of enormous industrial importance such as hydroformylation reactions (conversion of alkenes to aldehydes) and Pauson–Khand cycloaddition (production of cyclic ketones). Cobalt is an electron‐rich late transition metal, a property reflected throughout its organometallic chemistry. Thus, the carbonyl ‘hydride’ HCo(CO)4is actually a strong acid and does not have ‘hydridic’ (H−) properties. Similarly, cobalt does not complex to any group 15 or 16 heterocycles such as pyridine or thiophene. In contrast, boracycles are good ligands for cobalt in a sandwich complex because an electropositive atom such as boron incorporated in a π‐cyclic ring stabilizes the electron‐rich central metal. The cyclopentadienyl ligand is found extensively throughout organocobalt chemistry – not only in cobaltocenes, but also in half‐sandwich complexes of the type (C5H5)CoL2, where L is CO, alkene, alkyne, or phosphine. The (C5H5)CoL2complexes are useful in alkyne dimerization and trimerization. Cobaltocene itself ((C5H5)2Co) is easily oxidized to the extraordinarily stable 18‐electron cobaltocenium cation, [(C5H5)2Co]+. Cobalt can be incorporated into carborane cages, which have been found to be efficient extractors of radioactive metal ions such as90Sr and137Cs in water at low pH. Cobalamins, which consist of a cobalt central atom in a substituted corrin ring, are examples of naturally occurring organometallic compounds, and coenzyme B12was the first recognized example of a biological organometallic compound. Methylcobalamins play a role in biology, where they are found in microorganisms and can methylate mercury in the environment.
Electrochemistry: Applications in Inorganic ChemistryBased in part on the article Electrochemistry: Applications in Inorganic Chemistry by Robert H. Crabtree which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Holden Thorp H. 
Published: December 2011

AbstractBecause of the redox versatility of many transition metal complexes, electrochemical methods are an important part of the inorganic chemist's experimental repertoire. This article centers mostly on the use of cyclic voltammetry, where current is measured as the potential is varied linearly with time. Cyclic voltammetry is the primary method used by inorganic chemists, but many pulsed voltammetric provide complementary, and often useful, information. Theoretical methods now offer the means to calculate redox potentials of metal complexes, which can be correlated with values determined by cyclic voltammetry. Digital simulation techniques also now provide the ability to determine mechanistic information from voltammograms by directly calculating expected responses based on input mechanisms. Frontier applications of electrochemistry in inorganic chemistry involve the application of redox cycling to molecular memory.
Electron Transfer in Coordination Compounds
Authors: Endicott John F. 
Published: December 2011

AbstractThe transfer of an electron between a transition metal donor and a transition metal acceptor can be promoted by the absorption of either thermal or light energy. The thermal processes have been experimentally determined to span a range of about 1020in their ambient rates of electron transfer. The same molecular properties that determine the electron‐transfer reactivity also determine the correlated electron‐transfer absorption or emission band energy, band shape, and absorptivity. The relationships between the thermal‐kinetic and the spectroscopic observations are relatively simple when there is very little electron delocalization between the donor and acceptor, the weak‐coupling limit. This limit applies to most bimolecular electron‐transfer reactions of transition metals and to the spectroscopy of transition metal ion pairs; this is the limit treated well by Marcus theory. When the donor and acceptor are covalently linked, interactions of the donor and acceptor with the linker often increase the coupling in such a way as to enhance the reactivity and to alter the spectroscopy. Most of these linker‐induced changes of reactivity and spectroscopy can be treated in terms of perturbation theory‐based alterations of the behavior in the weak‐coupling limit. Reactivity in some very strongly coupled complexes seems to fall outside the standard theoretical framework; many such systems seem to implicate nuclear motions of the linker in facilitating the donor–acceptor electronic coupling. Extensions to biological, multicentered, and heterogeneous systems containing transition metal complexes are briefly considered.
Germanium: Inorganic ChemistryBased in part on the article Germanium: Inorganic Chemistry by Frank Glockling which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Qin Chao , Gao Lei , Wang Enbo 
Published: December 2011

AbstractIn this article, the basic physical and chemical properties, preparation, and applications of germanium and its related compounds are all described in detail. The whole chapter is divided into 12 sections, namely, introduction, analysis, the element, hydrides, boron derivatives, nitrogen compounds, phosphorus and arsenic compounds, oxygen‐bonded compounds, sulfides, selenides and tellurides, halides, metalloid‐ and metal‐bonded compounds, and polyoxometalates of germanium. In each section, some new development in the synthesis and applications of new compounds are included following the fundamental information.In the introduction section, the discovery, distribution, effect on organisms, basic chemistry, and application of germanium are given briefly.The analysis section gives a concise description of the main analysis processes.The preparation, basic physical and chemical properties of metal germanium, and anionic germanium clusters are included in the element section.In the following sections, different germanium compounds are described mainly according to the different valence germanium exhibits. Their fundamental synthetic routes, discovery and synthesis of new compounds, and the new development in the related fields are emphasized. In particular, contents concerning the construction of framework materials, the synthesis of polyoxometalates, which represent the tendency of development in inorganic chemistry, are presented comprehensively.More than seventy equations are used to illustrate certain reactions, and detailed information of some important compounds and their synthetic routes are also given in the form of structures, schemes, and figures. Certain data, properties and structure information of germanium, and its compounds are listed in some tables.Related articles are also given following the main content with the details explained in the text.This article containing extensive contents about germanium should provide a basic resource for reference of the related studies. An explanation of the development of the recent germanium chemistry may provide insight into the exploration of new fields.
Halides: Solid‐State ChemistryBased in part on the article Halides: Solid State Chemistry by Gordon J. Miller which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Köhler J. 
Published: December 2011

Abstract
This review on binary metal halides demonstrates their enormous richness of structural topologies as well as compositions. It emphasizes thermodynamic stabilities, influences of size and electronegativity effects, the intricate balance of ionic and covalent metal–halide and metal–metal interactions, and effects of excess valence electrons of atoms with nonclosed shells, in order to outline relationships of structure and bonding. The most important structure types of the main group metal halides are given and pressure effects are discussed. Selected examples show the influence of the stereochemical activity of lone pairs of electrons in reduced halides. Halides of the transition elements are discussed according to their empirical formulas in order to correlate structure and properties with d electron concentration at the metal atoms, which are based on typical Jahn‐Teller distortions or the formation of metal–metal bonded units. Finally, a summary of the rare earth element halides is given.
Hydrodesulfurization & Hydrodenitrogenation
Authors: Angelici Robert J. 
Published: December 2011

AbstractHydrodesulfurization (HDS) and hydrodenitrogenation (HDN) are large‐scale commercial processes that occur when petroleum feedstocks are treated with hydrogen (H2) at moderately high pressures and temperatures. During the reactions, the organosulfur and organonitrogen molecules liberate H2S and NH3. The process results in the production of hydrocarbon fuels with low levels of sulfur and nitrogen. Such fuels are necessary in order to prevent pollution of the atmosphere by sulfur and nitrogen oxides. The HDS and HDN processes are catalyzed by heterogeneous catalysts consisting of molybdenum and cobalt sulfides supported on alumina. Because it is experimentally impossible to determine details of the HDS and HDN processes as they occur on catalyst surfaces, detailed transformations that may occur on the catalyst are modeled by reactions that occur in transition metal complexes that can be fully characterized. As models for the adsorption of thiophenes, benzothiophenes, indoles, and quinolines on metal sites of the catalyst surface, these organosulfur and organonitrogen compounds are coordinated to metals in a variety of complexes. This coordination occurs through the sulfur or nitrogen atom or through π‐bonds in the hydrocarbon portion of the molecules and depends on the electronic state of the metal center. Once coordinated to a metal center, the organosulfur or organonitrogen compound is activated in ways that lead to the cleavage of CS and CN bonds, which are also reactions that occur in the heterogeneous HDS and HDN reactions. Patterns of reactivity of organosulfur and organonitrogen compounds in their metal complexes are used to propose detailed mechanisms for the steps that lead to the formation of H2S and NH3in the catalytic processes. The validity of these mechanisms has been tested in a range of isotopic labeling, spectroscopic, and reactivity investigations on the heterogeneous catalysts. Not only have the studies of organosulfur and organonitrogen complexes provided a basis for understanding and potentially improving the HDS and HDN processes, they have led to new approaches to the removal of sulfur and nitrogen and to new transformations of organosulfur and organonitrogen compounds.
Hydrogen: Inorganic Chemistry
Authors: Kakiuchi Masahisa 
Published: December 2011

AbstractThe properties of behavior of hydrogen and its isotopes, and the various applications of hydrogen are presented and discussed. The natural occurrence, preparation, use, and analysis of hydrogen are described. The atomic properties of protium (H), deuterium (D), and tritium (T) and the major physical properties of isotopic molecular hydrogen and isotopic water molecules are compared, and the distribution of deuterium and tritium in nature is geochemically discussed. Isotope effects concerning the vapor pressure and the fractionation factor of hydrogen and water molecules in equilibrium are explained, and are expanded in aqueous solutions. The chemical properties of atomic and ionized hydrogen, the reactions of molecular hydrogen, and the absorption and adsorption of hydrogen are compiled. The topics of the hydrogen spectroscopy, the ortho‐ and para‐hydrogen, the hydrogen in semiconductor, and the hydrogen energy are also compiled.
Iridium: Inorganic & Coordination Chemistry
Authors: Housecroft Catherine E. 
Published: December 2011

AbstractThis article provides an overview of the inorganic and coordination chemistry of iridium, beginning with a summary of physical properties, accessible oxidation states, and common coordination geometries. Solid‐state compounds are summarized with pertinent examples. Mononuclear compounds and complexes are classified according to the oxidation state of the iridium center and the donor atom(s) of the ligand; dinuclear and multinuclear complexes are discussed in a separate section. References make use of review articles where appropriate, as well as the primary literature. It is not the aim of this article to provide a comprehensive survey of the chemistry of iridium.