bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability Constants & Their DeterminationBased in part on the article Stability Constants & Their Determination by Harry M. N. H. Irving which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Hutton Alan T. , Linder Peter W. 
Published: March 2006

Abstract

This article is concerned with quantitative aspects of reactions in solution between metal ions and ligands to form complexes. The equilibrium constants of these reactions are usually called
stability constants
or
formation constants
. Formal definitions are presented of stability constants and a distinction is made between thermodynamic constants (activity quotients) and stoichiometric constants (concentration quotients). The practical difficulties of determining thermodynamic constants are discussed and the general resort to measuring stoichiometric constants and its implications are rationalized. The important idea and usefulness of formation curves for a given metal–ligand system are described. Mention is made of old‐fashioned curve‐fitting procedures for processing the relevant experimental data and references are given to the currently more important computer programs that have been developed for the purpose. Brief descriptions, especially of the underlying principles, are given of a selection of the experimental methods that have been developed for determining stability constants, that is, potentiometry, voltammetric methods (polarography and anodic stripping voltammetry), pH‐metry, competitive equilibria, use of cation exchange resins, liquid–liquid partition, spectophotometric methods, and nuclear magnetic resonance spectroscopy. Mention is made of a few other methods. pH‐metry is by far the most widely used and arguably the most sensitive and accurate of all the methods that have been developed. Justification for the considerable effort that has been, and continues to be, put into determining stability constants is presented in a section that summarizes the uses of stability constants. In particular, applications considered are to extraction metallurgy, the nuclear energy industry, analytical methods, and to medical, environmental, and industrial research. These applications all require stability constant values of high reliability and sources of critically evaluated published constants are referenced. Finally, a summary is presented of contributions that have been made to some fundamental ideas of chemistry arising from consideration of stability constant values.
Sulfur: Organic PolysulfanesBased in part on the article Sulfur: Organic Polysulfanes by Ralf Steudel & Monika Kustos which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Atwood David A. , Zaman M. Kamruz 
Published: March 2006

AbstractOrganic polysulfanes are compounds of the type RSnR with n > 2. They may be chain‐like or cyclic. The organic residues (alkyl or aryl) are linked to the sulfur atoms via carbon atoms. In the literature these compounds are often termed as organic polysulfides, but the IUPAC recommended nomenclature is polysulfanes. Sulfur‐rich organic polysulfanes can be viewed as intermediates between organic and inorganic compounds. On one hand, they are characterized by organic substituents R, which terminate the sulfur chain or close this chain to form a ring. On the other hand, compounds with sulfur chains of three or more sulfur atoms are ‘inorganic’ enough to attract the interest of inorganic chemists who have contributed much to this area. Organic polysulfanes with up to 16 sulfur atoms in the molecules have so far been obtained as pure substances, but species with up to 35 sulfur atoms in a chain or ring have been prepared in mixtures. Organic polysulfanes play an important role not only in basic research and industry, they are also found as natural products in organisms and occur in the inanimate nature. The main importance of organic polysulfanes comes, however, from their role in the large scale industrial vulcanization of natural and synthetic rubber. In this article, the preparation, structure, modern analysis, basic reactions, natural occurrence, biological activity, and practical importance of organic polysulfanes with three or more neighboring sulfur atoms in a chain or ring have been presented.
SuperconductivityBased in part on the article Superconductivity by Jeremy K. Burdett which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Poole Charles P. , Farach Horacio A. 
Published: March 2006

Abstract
Superconductivity occurs in a material below its characteristic transition temperature. It is defined in terms of its two significant properties, that is, zero electrical resistance, and perfect diamagnetism. There are two characteristic lengths, the penetration depth for magnetic field penetration, and the coherence length, which measures the size of the supercurrent carriers called Cooper pairs. Supercurrents or persistent currents can flow indefinitely without loss. Elements are Type I superconductors, which totally exclude magnetic fields from their interior, and compounds are Type II superconductors, which partially exclude these fields. The application of an applied magnetic field greater than a critical field, and an applied electric current density exceeding a critical density, converts a superconductor to the normal state. Superconducting elements, alloys, and compounds are discussed, including borocarbides, Chevrel compounds, Laves phases, heavy fermions, A‐15 compounds, organics, alkali doped fullerenes, and cuprates or high‐temperature superconductors.
Tellurium: Organotellurium ChemistryBased in part on the article Tellurium: Organotellurium Chemistry by William R. McWhinnie which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Laitinen Risto S. , Oilunkaniemi Raija 
Published: March 2006

Abstract
Chemistry of organotellurium compounds has developed very rapidly during the recent decades. Tellurium reagents find uses in synthetic organic chemistry. Organometallic complexes with tellurolato or telluroether ligands show potential application in the fabrication of new materials for electronic devices. The present review emphasizes the preparation and structural characterization of some main classes of organic tellurium compounds and their organometallic complexes that are deemed of interest for inorganic chemists.
Thallium: Inorganic Chemistry
Authors: Tóth Imre , Győri Béla 
Published: March 2006

Abstract
Classical knowledge of thallium inorganic chemistry is summarized in the article. The introduction consists of the history, occurrence and distribution, production, and use of this trace element. The properties of thallium(I) and thallium(III) are discussed by the short description of the most important inorganic compounds: hydrides, halides and pseudohalides, oxides, hydroxides, ternary, and more complex oxides, chalcogenides, salts with oxoanions, complexes with multidentate organic ligands, metal–metal bonded Tl‐complexes. The toxicity and the analytical methods are also shortly discussed.
Thallium: Organometallic ChemistryBased in part on the article Thallium: Organometallic Chemistry by William S. Rees, Jr. & Gertrud Kräuter which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Pike Robert D. 
Published: March 2006

AbstractThe organometallic chemistry of thallium(I) is dominated by cyclopentadienyl complexes. These may be polymeric through bridging Cp arrangements or oligomeric as a result of Tl⋯Tl contacts. ThCp complexes are easily prepared and are highly useful Cp‐transfer agents. There are two known Tl(I) organometallics with direct TlC σ‐bonds; one is monomeric and the other is tetrameric due to Tl⋯Tl contact. A variety of Tl(I) π‐complexes are recognized. Bonding in the latter tends to be fairly weak.Two R2TlTlR2dimers (R = silyl group) are known, but no such Tl(II) complexes are known for carbon ligands. The chemistry of organothallium(III) compounds is more extensive, encompassing such species as R3Tl, R2TlX, RTlX2(X = anionic ligand), and complexes of these species with additional ligands. A wide array of X‐ray crystal structures for Tl(III) complexes reveals monomeric, oligomeric, and polymeric arrangements, with bridging ligands being very common.Thallium compounds are highly toxic and should be handled with great care. Volatile Tl species are of use in the chemical‐vapor deposition of superconducting phases. Finally, Tl(III) salts are fairly important reagents in organic syntheses, especially in oxidations and in ring expansion and contraction reactions.
Transition Metal Carbonyls: Infrared Spectra
Authors: Timney John A. 
Published: March 2006

Abstract
The number, pattern, and position of the CO‐stretching absorptions (ν(CO)) of transition metal carbonyls gives considerable information about molecular structure, symmetry, and bonding. This article deals with the processing of the basic data (number, frequency, and intensity of ν(CO) bands) to give useful information about carbonyl‐containing organometallic compounds via an ‘energy factored force field’ (EFFF). The reasons why the EFFF works so well and the relationships between different types of force constant within the EFFF are examined. The application of these force constants in elucidating molecular structure is discussed, together with the very successful ligand effect model that enables chemists to predict ν(CO) frequencies with remarkable accuracy.
Tungsten: Inorganic & Coordination Chemistry
Authors: McCleverty Jon A. 
Published: March 2006

Abstract
The inorganic and coordination chemistry of tungsten is described, being presented according to ligands and/or donor atom sets (halides, cyanides, and other ligands containing group IV atoms, ligands containing O, S, Se, Te, N, P, Sb, Bi, or, As donor atoms, hydrides, and borohydrido ligands) and are discussed in relation to the oxidation state. Special mention is made of metal–metal bonded dinuclear species, a brief description of polyoxoanionic species is given, and tri‐ and tetranuclear cluster compounds and some species of higher nuclearity, containing chalcogenide atoms, are described.
Vanadium: Organometallic ChemistryBased in part on the article Vanadium: Organometallic Chemistry by Dieter Rehder which appeared in theEncyclopedia of Inorganic Chemistry, First Edition.
Authors: Hirao Toshikazu 
Published: March 2006

AbstractThis review surveys the chemistry of organovanadium compounds. Their syntheses and reactivities are described depending on the coordination‐binding mode.
Zinc:DNA‐Binding Proteins
Authors: Pennella Mario A. , Giedroc David P. 
Published: March 2006

AbstractZinc‐containing nucleic acid‐binding proteins are ubiquitous in nature and interact with all types of nucleic acids, including ssDNA, duplex DNA, and RNA. The primary role played by these Zn(II) coordination complexes is to provide local or global stability to these proteins that function in transcriptional regulation, DNA metabolism, and nucleic acid packaging. These proteins are now broadly designated as zinc finger (zf) proteins. Six structural classes of zf proteins are discussed here that are distinguished from one another on the basis of the secondary and tertiary structure of the zf domain, the nature of the ligating side chains (Cys and/or His), and the linear spacing of amino acid ligands in the primary structure. These structural zinc sites are compared with metalloregulatory zinc coordination complexes found in metal‐sensing transcriptional regulatory proteins that control zinc homeostasis in bacteria (e.g.E. coliZurR and ZntR;S. aureusCzrA;SynechococcusSmtB), lower eukaryotes (S. cerevisiaeZap1), and mammalian cells (MTF‐1). Structural and functional comparisons of the bacterial zinc sensors with homologous sensors specific for other transition metal ions (e.g. Cu, Ni, Mn) and xenobiotics (e.g. Cd, Pb, and Hg) suggest that coordination number and therefore geometry are primary determinants of metal selectivity of metal sensor proteins in vivo.
Zinc Enzymes
Authors: Auld David S. 
Published: March 2006

AbstractA remarkable mosaic of zinc‐binding motifs influence the function of proteins involved in all aspects of metabolism, providing evidence on the molecular level for the indispensability of zinc to growth and development and transmission of the genetic message. There are now about 400 three‐dimensional structures for zinc proteins, representing all six classes of enzymes and covering a wide range of phyla and species. These structures provide standards of reference for the identity and nature of zinc ligands in other proteins for which only the primary structure is known. Three primary types of zinc sites are apparent from examination of these structures: structural, catalytic, and cocatalytic. The most common amino acids that supply ligands to these sites are His, Glu, Asp, and Cys. In catalytic sites, zinc generally forms complexes with water and any three nitrogen, oxygen, and sulfur donors with His being the predominant amino acid chosen. Water is always a ligand to such sites. Structural zinc sites have four protein ligands and no bound water molecule. Twelve of the twenty‐two permutations of four Cys, His, Glu, and Asp ligands have been observed. Cys is the preferred ligand in such sites. Cocatalytic sites contain two or three metals in close proximity with two of the metals bridged by a side‐chain moiety of a single amino acid residue, such as Asp, Glu, or His and sometimes a water molecule. Asp and His are the preferred amino acids for these sites. The properties of both H‐bonding and hydrophobic amino acid ‘outer shell ligands’ and the secondary support structure of the zinc sites is important to the function, stability, and reactivity of the bound metal. The influence of zinc on quaternary protein structure has led to the identification of a fourth type of zinc‐binding site, protein interface. In this case, zinc sites are formed from ligands supplied from amino acid residues residing in the binding surface of two proteins. The resulting zinc site usually has the coordination properties of a catalytic or structural zinc‐binding site.
Zinc: Organometallic ChemistryBased in part on the article Zinc: Organometallic Chemistry by Gerard Parkin which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Grévy Jean‐Michel 
Published: March 2006

Abstract

Since the discovery of the first organozinc compounds by Sir Edward Frankland in 1849, the organometallic chemistry of zinc made remarkable advances and organozinc species have become essential tools for organic chemists. During the past decade, numerous new and modified procedures for the preparation of the title compounds have been published, rendering their synthesis easier, faster, and less expensive and giving higher yields. The coordination chemistry of organozinc derivatives has been subject of further interest and various intra‐ and intermolecular complexes with different donor ligands have been structurally characterized by X‐ray crystallography and spectroscopic methods. The accumulation of molecular structures, physicochemical studies, and computational calculations has led to a better understanding of the organozinc chemistry, and consequently to the design of new derivatives for specific applications. Even if the development of areas like the chemistry of organozinc anions and cations is still in its early stage, these compounds, which exhibit properties different than those of the parent organometallic species, appear to have promising applications in synthesis and catalytic reactions. During the past ten years, the chemistry of organo‐
gem
‐dizincio derivatives has also been the subject of much interest and progress. These reagents can form two carbon–carbon bonds in a one‐pot reaction and with high stereoselectivity. They became key reagents for organic chemists who want to combine multiple transformations in one operation. The importance of organometallic compounds of zinc can be seen in the growing number of their applications in synthesis. They are used in many reactions such as substitutions, additions to carbonyl compounds and unsaturated systems, cyclopropanations, and polymerizations. Furthermore, as a result of their low reactivity, they tolerate a wide variety of functionalities and perform most of the transformations with high regio‐ and enantioselectivity. After spending more than half a century in the shade of Grignard and organolithium reagents, organozinc reagents are becoming more and more important in modern chemistry.
Zirconium & Hafnium: Inorganic & Coordination ChemistryBased in part on the article Zirconium & Hafnium: Inorganic & Coordination Chemistry by Grigorii L. Soloveichik which appeared in the
Encyclopedia of Inorganic Chemistry, First Edition
.
Authors: Kozak Christopher M. , Mountford Philip 
Published: March 2006

Abstract
The inorganic and coordination chemistry of zirconium and hafnium is described. The physical properties of the metals, as well as their isolation, purification, and commercial and industrial uses are discussed. A section on the binary compounds of zirconium and hafnium containing hydride and main group elements follows. Oxoacid salts of the two metals are described, as well as aqueous chemistry. Examples of zirconium and hafnium coordination chemistry are presented according to ligand type: molecular and silica‐supported hydride complexes; ionic and neutral halide complexes; complexes with oxygen donor ligands; complexes with nitrogen donor ligands; dinitrogen complexes; complexes with phosphorus and sulphur donors ligands; complexes with mixed‐donor ligands. Lastly, lower oxidation state inorganic, coordination, and cluster compounds are discussed.
Biomimetic Synthesis of Nanoparticles
Authors: Slocik Joseph M. , Knecht Marc R. , Wright David W. 
Published: March 2006

Abstract

Biological systems provide numerous examples of highly controlled biomineralization processes that result in stabilized nanoparticles with superior optical properties, crystallinity, dispersity, and morphology. This is best exemplified by the selective mineralization of ferrihydrite (FeOOH·3H
2
O) as a labile source of iron within the iron storage protein ferritin. Consequently, these processes have inspired the use of biomolecular templates to mediate and mimic the synthesis of nano‐materials with a remarkable degree of success. Biomimetic approaches to nanoparticle synthesis include the use of single amino acids, small synthetic peptides (3–18 residues), phage displayed peptides, combinatorial libraries, native proteins, and plant viruses. In the following, we present these biologically inspired templates and methodologies; in addition to describing nanoparticle characterization, resultant properties, and implications for the nanoscale synthesis of materials.
Metal‐Related Diseases of Genetic Origin
Authors: Sarkar Bibudhendra 
Published: March 2006

AbstractIn humans, there are several genetic disorders of metal metabolism. Wilson and Menkes diseases are genetic disorders of copper transport. The genes from these two diseases encode copper‐transporting ATPases. Mutations in Wilson disease gene cause toxic accumulation of copper in the cells whereas mutations in Menkes disease gene cause copper deficiency and lack of its incorporation in important copper enzymes. Wilson disease is treated by chelating agents such asD‐penicillamine and trientine and zinc, which inhibits absorption of copper from the intestine. Current treatment for Menkes disease is subcutaneous injection of copper‐histidine. Hereditary hemochromatosis, thalassemia, and aceruloplasminemia are major disorders of iron metabolism. The gene responsible for hereditary hemochromatosis encodes a protein, which is very similar to major histocompatibility complex on chromosome 6, that has been proposed to down‐regulate iron absorption. The disease is treated by weekly venesection of approximately 0.5 L of blood. Thalassemia causes severe iron accumulation as a result of disturbances in the synthesis of one or more of the globin chains of hemoglobin. The chelating agent used for the treatment is deferoxamine administered subcutaneously. The search for an orally administered iron chelator has been intensified in recent years leading to chemical trials of chelator such as deferiprone (L1). Aceruloplasminemia is caused by mutations in the ceruloplasmin gene resulting in iron accumulation in various tissues. Deferoxamine has been used to treat this disease. Acrodermatitis enteropathica is a genetic disorder of zinc metabolism. Mutations in the gene responsible for zinc transport result in insufficient absorption of zinc in this disease, which can be ameliorated by zinc supplementation. Several less common genetic disorders of metal metabolism are discussed briefly.
Long‐Range Electron Transfer in Biology
Authors: Winkler Jay R. 
Published: March 2006

Abstract

Electron‐transfer processes are vital elements of energy transduction pathways in living cells. A unique synergy between theory and experiment has produced an extraordinarily detailed understanding of the factors that regulate this ‘current of life’. Studies of Ru‐modified proteins have provided insights into the distance‐ and driving‐force dependences of intraprotein electron transfer rates. Electron transfer across protein–protein interfaces has been probed both in solution and in structurally characterized crystals. It is now clear that electrons tunnel between sites in biological redox chains, and that protein structures tune thermodynamic properties and electronic coupling interactions to facilitate these reactions. This research has produced an experimentally validated, electron tunneling timetable that predicts the time required for an electron to transfer across a specified distance in a protein. Many of the electron tunneling rates measured in cytochrome
c
oxidase and photosynthetic reaction centers agree well with timetable predictions, indicating that the natural reactions are highly optimized, both in terms of thermodynamics and electronic coupling.
Metal‐Based Drugs
Authors: Shaw C. Frank 
Published: March 2006

AbstractMetallopharmaceuticals have a long history in the development of chemotherapy. The more recent success of cisplatin and six related Pt‐based antitumor drugs, and longer histories of chrysotherapy (gold treatments) for arthritis, bismuth antiulcer agents, and silver‐, antimony‐ and arsenic‐based antimicrobial agents demonstrate that the periodic table represents a potential wealth of medicinal agents to be explored and developed in the future. This article reviews the use of twelve elements (Ag, As, Au, Bi, Ga, Li, Pt, Ru, Sb, Sn, Ti, V) for a wide variety of diseases and disorders. The current state of research on particular applications varies widely – from promising treatments that have not yet reached the clinic to those that are well established empirically despite uncertain mechanisms of action. The array of antitumor agents licensed or in clinical trials includes compounds of As, Ga, Ru, and Ti, in addition to platinum. There are also exciting efforts to apply known treatments or biological properties to new diseases by taking advantage of extensive databases, for example, developing antitumor agents from organotin complexes that have long been used as fungicides and antifouling agents, and antimicrobial agents from gold complexes. The ability to modulate the properties of metal complexes by choice of the oxidation state (AuIvs AuIII; PtIIvs PtIV; VIII, VIV& VV, etc.) and design of the medical carrier ligands (e.g. 1,2‐diaminocyclohexane vs two ammine ligands for Pt antitumor agents) allows targeting of particular tissues or cells and balancing of lipophilicity, solubility, and reactivity to balance therapeutic activity against toxicity. Many, if not most, metallopharmaceuticals are prodrugs that undergo redox changes and/or ligand exchange reactions in vivo to generate the active species. Hence, research on metallodrug metabolism and pharmacology is as important as the initial medicinal screening of the agents.