bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copper Proteins with Dinuclear Active SitesBased in part on the article Copper Proteins with Dinuclear Active Sites by Konrad Lerch which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Decker Heinz 
Published: March 2006

Abstract
Copper proteins with dinuclear active sites comprise proteins with different structures and functions. The phenoloxidase, tyrosinase, and catecholoxidase are responsible for browning by starting the synthesis of melanin. These enzymes are involved in the primary immune response in invertebrates, plants, fungi as well as in the sclerotization of arthropods. The respiratory proteins hemocyanins are responsible for oxygen transport in some arthropods and molluscs. However, they can be converted to enzymes exhibiting phenoloxidase activity. Based on X‐ray structures of hemocyanins and a catecholoxidase, large parts of folding motifs are very similar although the sequence identities are far below 30%. A model for the activation process of phenoloxidase activity is presented.
Cyanide Complexes of the Transition MetalsBased in part on the article Cyanide Complexes of the Transition Metals by Timothy P. Hanusa & David J. Burkey which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Hanusa Timothy P. 
Published: March 2006

Abstract

Cyano metal complexes contain one or more bound cyanide ligands, CN
−
, and constitute one of the largest and longest‐known classes of compounds in inorganic chemistry. Like carbon monoxide, the cyanide ion can function as a π‐acid ligand, but because of its negative charge, the cyanide ion can also form strong sigma bonds. This bifunctional behavior allows CN
−
to stabilize both high and low oxidation states of metals. The cyanide ion can bind to metals in both terminal and bridging (MCNM′) modes; the bridges are commonly linear, and are present in Prussian blue and many other polymeric metal cyanides. Framework solids with high degrees of void space can be formed with bridging cyanide ligands. Cyano metal complexes undergo a variety of oxidation‐reduction reactions, but owing to the strong σ‐donor properties of CN
−
, only a few ligands are capable of directly replacing metal‐bound cyanide. For most substitution reactions, photochemically induced dissociation of one or more of the CN
−
ligands is needed. Cyano complexes are used as pigments and dyes, and are being increasingly explored as electroactive, zeolitic, and chemical sensing materials.
Cytochrome OxidaseBased in part on the article Cytochrome Oxidase by Gerald T. Babcock which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Wikström Mårten 
Published: March 2006

AbstractHeme‐copper oxidase is the current generic name for the superfamily of respiratory enzymes that are responsible for cell respiration in the mitochondria of eukaryotic cells as well as in aerobic prokaryotes, and which shows substantial structural and functional homology among its members. This group of enzymes is responsible for more than 90% of the consumption of dioxygen by living organisms on this planet. Harnessing the high oxidizing power of the O2/H2O redox couple some 2.5–3 billion years ago made a revolutionary impact on evolution. The oxidation of foodstuffs by O2gave an approx. 15‐fold energetic advantage over previously predominant glycolytic oxidations, and was the prerequisite for the development and evolution of all higher multicellular organisms. Apart from mastering the O2reduction chemistry in a safe and economical fashion, these enzymes also function as remarkable energy transducers that convert much of the free energy released in the process into a proton gradient, which is subsequently used to drive virtually all energy‐requiring processes in the cell. This article reviews the major advances in the last 10 years of research on this group of enzymes. The major highlights are the elucidation of the crystal structures of several oxidases, major advances in the understanding of the mechanism of O2activation and reduction at the bimetallic heme iron‐copper active site, and recent progress in the ongoing research on the perhaps most intriguing but least known function, redox‐coupled proton translocation.
Defects in Solids
Authors: Tilley Richard J. D. 
Published: March 2006

Abstract
The chemical aspects of defects of relevance to inorganic crystalline solids are described, especially the close links with the composition of crystalline nonmetallic inorganic nonstoichiometric compounds. The discussion begins with a description of simple point defects in stoichiometric materials and the relationship between the population of these defects and the Gibbs energy of formation of the defects. This includes defects in monatomic structures and balanced populations of point defects, Frenkel and Schottky defects, in binary compounds. Superionic compounds that contain quasi‐liquid cation arrays are considered as extreme cases of these simpler defect populations. Nonstoichiometric compounds treated from the standpoint of small populations of point defect populations are considered, including color centers. Defect chemistry, the incorporation of point defects into chemical nomenclature, is described, including the Kroger–Vink notation and the construction of Brouwer diagrams. Grossly nonstoichiometric compounds, including those that can be considered to contain point defects or structurally organised defect clusters, such as the iron oxide wüstite, and the defect fluorite structures are illustrated. Extended defects portray a wider view of defect chemistry, in which planar faults and intergrowths are prominent structural features of many complex inorganic solids. To illustrate planar defects, examples are taken from crystallographic shear phases, twinned structures, intergrowth structures, and the niobium oxide block structures. Structures containing pentagonal columns linked by vertices provide an example of structures that contain columnar defects. Examples of inorganic solids that possess more than one defect type are taken from layered perovskite phases, tungsten bronzes, and high‐temperature ceramic superconductors. The final section is concerned with structures that were once described as containing defects but that have recently been found to be essentially defect free. These materials, in which defects are eliminated by the device of continuous structural modulation affecting one part of the structure, are widespread over many classes of inorganic solids. Examples drawn from oxides related to tantalum pentoxide, layer misfit phases, and anion‐excess fluorite‐related materials.
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: March 2006

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: March 2006

Abstract

The 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 10
20
in 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.
Electronic Structure of Organometallic Compounds
Authors: Albright Thomas A. 
Published: March 2006

Abstract

A brief treatment of the concept of orbital interaction is given, particularly in reference to the transition metal‐ligand bond. This is then applied to the σ splitting pattern for the ML

n

series where
n
= 6, 5, 4 (square planar and tetrahedral), 3, and 2 cases. Here M is a transition metal and L is a generic ligand with a σ donor function. A description is given for how the splitting pattern is modified when one or more of the ligands have π acceptor or donor functions. Several examples illustrate how symmetry can sometimes create modification to the normal electron counting rules. A detailed discussion is given of how to create the important valence orbitals of an ML

n

fragment and several examples are given of their use to build up the orbitals of large organometallic molecules. Finally, a detailed discussion is given of the construction and use of the isolobal analogy.
Electronic Structure of Solids
Authors: Canadell Enric 
Published: March 2006

AbstractThe basic language needed to understand the electronic structure of solids is introduced. The approach is chemically oriented and the notion of orbital interaction, so useful to understand the electronic structure of molecules, is used as much as possible. A step‐by‐step approach to the electronic structure of several solids is discussed. Notions like Density of states (DOS), Fermi surface (and nesting), Peierls distortions, charge and spin density waves (CDW/SDW), and COOP (crystal orbital overlap population) curves are presented and analyzed with reference to selected examples. The role of electron repulsions is also considered. The relationship between the electronic structure and the structural and transport properties of solids is discussed. A brief account of the more commonly used computational approaches for solids is also presented.
Fluorine: Inorganic ChemistryBased in part on the article Fluorine: Inorganic Chemistry by Darryl D. DesMarteau, Charles W. Bauknight, Jr., & Todd E. Mlsna which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Atwood David A. 
Published: March 2006

AbstractThis article provides an overview of the extensive and diverse inorganic chemistry of fluorine. Key topics are covered, such as the methods used for the formation of element–fluorine bonds with hydrogen fluoride and elemental fluorine. The article includes a general description of the structure and bonding of common fluorine compounds and the various spectroscopic techniques for their characterization. More specific details are provided for the fluoride compounds of boron, and the groups 14–17 elements. New topics such as the means by which carbon–fluorine bonds may be broken and the fluorination of carbon‐based materials such as fullerenes and nanotubes are included in the appropriate sections.
Gallium: Inorganic ChemistryBased in part on the article Gallium: Inorganic Chemistry by Andrew R. Barron which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Banger Kulbinder Kumar , Hepp Aloysius F. 
Published: March 2006

AbstractAn overview of the inorganic chemistry of gallium and its compounds is reported in detail with an attempt to bring up to date current studies in this field. In addition, the use of various Ga related alloys as either binary or ternary semiconducting material for bulk, thin film, and nanotechnology is reported in detail pertaining to their synthesis, properties, and application. The chemistry of Ga inorganic and coordination derivatives is also reviewed and discussed.
Gallium: Organometallic ChemistryBased in part on the article Gallium: Organometallic Chemistry by Andrew R. Barron which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Robinson Gregory H. 
Published: March 2006

Abstract
The organometallic chemistry of gallium has experienced substantial growth over the past decade. Much of this work concerned the development of the organometallic chemistry of compounds containing GaGa bonds. This would include simple dimeric compounds, gallium ring compounds, and small gallium clusters. This chapter will discuss the synthesis and structural aspects of these compounds.
Germanium: Organometallic Chemistry
Authors: Banaszak Holl Mark , Peck David R. 
Published: March 2006

AbstractThis article provides an overview of the organometallic chemistry from 1994 to 2004. Major advances in the formation and breaking of GeC bonds are discussed, as are advances in the physical characterization of these compounds. Recent advances in the formation of organogermanium species containing multiple bonds to germanium and the formation of germanium‐centered radicals and cations are delineated. Applications to the synthesis of germanium‐containing polymers are overviewed.
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: March 2006

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.
Hydrides: Solid State Transition Metal Complexes
Authors: Yvon Klaus , Renaudin Guillaume 
Published: March 2006

AbstractAt present, some 50 different homoleptic transition (T) metal hydride complexes are known to occur in over 127 compounds that cover 47 structure types. The complexes form with T elements from group seven (Mn) to closed d‐shell elements of group twelve (Zn). While the great majority are centred by one T‐metal atom and display up to nine terminal hydrogen ligands, some are centred by two (Ru, Pt), four (Rh, Ni), or more (Ru, Rh) and display both terminal and bridging hydrogen ligands, and/or TT metal bonds. The structural and electronic configurations are consistent with those usually found in coordination compounds. The complexes are stabilized by charge transfer from the surrounding cation matrix, are often 18‐electron, and less often 16‐ or 14‐electron. Some hydride structures show evidence for metal–metal interactions as in typically interstitial metal hydrides while others contain additional hydride anions (H−) bonded to electropositive metals only, such as in saline hydrides. No HH bond formation is observed. Most hydrides are nonmetallic and many are colored. Some, however, show hydrogenation induced complex formation and metal‐to‐insulator transitions. The systems generally display very high volume efficiencies for hydrogen storage but are thermally too stable and/or too expensive for practical applications. Thermodynamic data suggest that their enthalpy of formation scales with the thermal stability of the binary hydrides of the electropositive metal constituents.
Hydrocyanation by Homogeneous Catalysis
Authors: Casalnuovo Albert L. , McKinney Ronald J. , Tolman Chadwick A. 
Published: March 2006

Abstract
The homogeneous catalysis of hydrocyanation is discussed with particular reference to the hydrocyanation of butadiene to adiponitrile, as employed in the commercial synthesis of nylon. Nickel complexes with bulky phosphite ligands are most effective and the mechanism is discussed. Asymmetric versions of the reaction are also discussed.
Hydrodesulfurization & Hydrodenitrogenation
Authors: Angelici Robert J. 
Published: March 2006

Abstract

Hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) are large‐scale commercial processes that occur when petroleum feedstocks are treated with hydrogen (H
2
) at moderately high pressures and temperatures. During the reactions, the organosulfur and organonitrogen molecules liberate H
2
S and NH
3
. 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 H
2
S and NH
3
in 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: March 2006

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.
Hydrosilation CatalysisBased in part on the article Hydrosilation Catalysis by John F. Harrod which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Marschner Christoph 
Published: March 2006

Abstract
The addition of a hydrosilane across an unsaturated molecule is called hydrosilation. This can be catalyzed by a number of reagents among which transition metal compounds are most important. The reaction of a variety of different silanes with alkyl, alkoxy, and halogen substituents is well established. The unsaturated molecules involve alkenes, alkynes, and a huge number of different carbonyl compounds as well as combinations thereof. While hydrosilation of alkenes and alkynes can mainly be seen as a silylation method, the reaction with carbonyl compounds constitutes a formal reduction. Among the used catalyst systems hexachloroplatinic acid in isopropanol (Speier's catalyst) is most frequently used.
Mechanistically the transition metal catalyzed reaction of an alkene can be seen as an oxidative addition of the silicon hydrogen bond, followed by the migratory insertion of the coordinated alkene into the metal hydrogen or silicon bond and a final reductive elimination of the alkylsilane. The formation of vinylsilanes through the dehydrogenating silation reaction is a frequently occurring side reaction. Such by‐products are thought to be formed by β‐hydride elimination of an intermediate β‐silylalkyl metal complex.
The hydrosilation reaction can promote the transformation of a prochiral (alkene, ketone) to a potentially chiral molecule. It bears potential for asymmetric synthesis, which is currently heavily investigated. The reaction is equally popular for classical organic synthesis as well as for material science tasks such as the chemical bonding of a polymer to a surface.