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Borderline Hydrides
Borderline hydrides typically refer to hydrides formed of hydrogen and elements of the periodic table in group 11 and group 12 and indium (In) and thallium (Tl). These compounds have properties intermediate between covalent hydrides and saline hydrides. Hydrides are chemical compounds that contain a metal and hydrogen acting as a negative ion. Properties Borderline hydrides exhibit bonding characteristics between ionic and covalent bond types. A specific examples of a borderline hydride CuH, copper hydride, that appears as a spongy reddish-brown substance is a moderate reducing agent. It will catalytically oxidize hypophosphorous acid to phosphorous acid at room temperature, and it gives off hydrogen gas when subjected to heat. ZnH2 is also a solid at room temperature that breaks down at 90 °C, but even left alone decomposes over several days to zinc metal and hydrogen gas. Hydrogen telluride (H2Te) and hydrogen selenide (H2Se) are both borderline hydrides o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydride
In chemistry, a hydride is formally the anion of hydrogen( H−). The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. For inorganic chemists, hydrides refer to compounds and ions in which hydrogen is covalently attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids. The hydride anion is very rarely observed. Almost all of the elements form binary compounds with hydrogen, the exceptions being He, Ne, Ar, Kr, Pm, Os, Ir, Rn, Fr, and Ra. Exotic molecules such as positronium hydride have also been made. Bonds Bonds between hydrogen and the other elements range from highly to somewhat covalent. Some hydrides, e.g. boron hydrides, do not conform to classical electron-counting rules and the bonding is described in terms of multi-centered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Telluride
Hydrogen telluride is the inorganic compound with the formula hydrogen, H2telluride (chemistry), Te. A hydrogen chalcogenide and the simplest hydride of tellurium, it is a colorless gas. Although unstable in ambient air, the gas can exist at very low concentrations long enough to be readily detected by the odour of rotting garlic at extremely low concentrations; or by the revolting odour of rotting leeks at somewhat higher concentrations. Most compounds with Te–H bonds (tellurols) are unstable with respect to loss of H2. H2Te is chemically and structurally similar to hydrogen selenide, both are acidic. The H–Te–H angle is about 90°. Volatile tellurium compounds often have unpleasant odours, reminiscent of decayed leeks or garlic.Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. . Synthesis Electrolytic methods have been developed.F. Fehér, "Hydrogen Telluride" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tautomer
Tautomers () are structural isomers (constitutional isomers) of chemical compounds that readily interconvert. The chemical reaction interconverting the two is called tautomerization. This conversion commonly results from the relocation of a hydrogen atom within the compound. The phenomenon of tautomerization is called tautomerism, also called desmotropism. Tautomerism is for example relevant to the behavior of amino acids and nucleic acids, two of the fundamental building blocks of life. Care should be taken not to confuse tautomers with depictions of "contributing structures" in chemical resonance. Tautomers are distinct chemical species that can be distinguished by their differing atomic connectivities, molecular geometries, and physicochemical and spectroscopic properties, whereas resonance forms are merely alternative Lewis structure (valence bond theory) depictions of a single chemical species, whose true structure is best described as the "average" of the idealized, hypothe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dihydrogen Complex
Dihydrogen complexes are coordination complexes containing intact H2 as a ligand. They are a subset of sigma complexes. The prototypical complex is W(CO)3( PCy3)2(H2). This class of compounds represent intermediates in metal-catalyzed reactions involving hydrogen. Hundreds of dihydrogen complexes have been reported. Most examples are cationic transition metals complexes with octahedral geometry. Upon complexation, the H−H bond is extended to 0.81–0.82 Å as indicated by neutron diffraction, about a 10% extension relative to the H−H bond in free H2. Some complexes containing multiple hydrogen ligands, i.e. polyhydrides, also exhibit short H−H contacts. It has been suggested that distances 1 Å are better described as dihydride complexes (see figure). Characterization The usual method for characterization is 1H NMR spectroscopy. The magnitude of spin-spin coupling, ''J''HD, is a useful indicator of the strength of the bond between the hydrogen and deuterium in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accounts Of Chemical Research
''Accounts of Chemical Research'' is a semi-monthly peer-reviewed scientific journal published by the American Chemical Society containing overviews of basic research and applications in chemistry and biochemistry. It was established in 1968 and the editor-in-chief is Cynthia J. Burrows (University of Utah). Abstracting and indexing The journal is abstracted and indexed in: According to the ''Journal Citation Reports'', the journal has a 2020 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of citations of articles published in the last two years in a given journal, as i ... of 22.384. References External links * {{American Chemical Society Journals Chemical Research Publications established in 1968 Monthly journals English-language journals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hapticity
In coordination chemistry, hapticity is the coordination of a ligand to a metal center via an uninterrupted and contiguous series of atoms. The hapticity of a ligand is described with the Greek letter η ('eta'). For example, η2 describes a ligand that coordinates through 2 contiguous atoms. In general the η-notation only applies when multiple atoms are coordinated (otherwise the κ-notation is used). In addition, if the ligand coordinates through multiple atoms that are not contiguous then this is considered denticity (not hapticity), and the κ-notation is used once again. When naming complexes care should be taken not to confuse η with μ ('mu'), which relates to bridging ligands. History The need for additional nomenclature for organometallic compounds became apparent in the mid-1950s when Dunitz, Orgel, and Rich described the structure of the "sandwich complex" ferrocene by X-ray crystallography where an iron atom is ''"sandwiched"'' between two parallel cyclopen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Policy debate is an American form of debate competition in which teams of two usually advocate for and against a resolution that typically calls for policy change by the United States federal government. It is also referred to as cross-examination debate (sometimes shortened to Cross-X or CX) because of the 3-minute questioning period following each constructive speech. Evidence presentation is a crucial part of Policy Debate. The main argument being debated during a round of Policy is which team wins a system by which the debate should be evaluated (Framework) and who wins under this framework (gets the ballot). When a team explains why their impacts are "greater" than the opposition's impacts, they utilize the concept of "impact calculus." One team’s job is to argue that the resolution— the statement that we should make some specific change to address a national or international problem —is a good idea. Affirmative teams generally present a ''plan'' as a proposal for imple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethylzinc
Dimethylzinc, also known as Zinc methyl, DMZ, or DMZn is a colorless volatile liquid Zn(CH3)2, formed by the action of methyl iodide on zinc at elevated temperature or on zinc sodium alloy. :2Zn + 2CH3I → Zn(CH3)2 + ZnI2 The sodium assists the reaction of the zinc with the methyl iodide. Zinc iodide is formed as a byproduct. It has a disagreeable odor, and is pyrophoric. It has been of great importance in the synthesis of organic compounds. It is soluble in alkanes and often sold as a solution in hexanes. It belongs to the large series of similar compounds such as diethylzinc. History This substance was first prepared by Edward Frankland during his work with Robert Bunsen in 1849 at the University of Marburg. After heating a mixture of zinc and methyl iodide in an airtight vessel, a flame burst out when the seal was broken. In the laboratory, this synthesis method remains unchanged today, except that copper or copper compounds are used to activate the zinc. Uses Dimethyl zi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halide
In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluoride, chloride, bromide, iodide, astatide, or theoretically tennesside compound. The alkali metals combine directly with halogens under appropriate conditions forming halides of the general formula, MX (X = F, Cl, Br or I). Many salts are halides; the ''hal-'' syllable in ''halide'' and ''halite'' reflects this correlation. All Group 1 metals form halides that are white solids at room temperature. A halide ion is a halogen atom bearing a negative charge. The halide anions are fluoride (), chloride (), bromide (), iodide () and astatide (). Such ions are present in all ionic halide salts. Halide minerals contain halides. All these halides are colourless, high melting crystalline solids having high negative enthalpies of formation. Test ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper Sulphate
Copper sulfate may refer to: * Copper(II) sulfate, CuSO4, a common compound used as a fungicide and herbicide * Copper(I) sulfate Copper(I) sulfate, also known as cuprous sulfate, is an inorganic compound with the chemical formula Cu2 SO4. It is a white solid that has attracted little attention, in contrast to copper(II) sulfate. It is an unusual example of a copper(I) ..., Cu2SO4, which is uncommonly used * Copper(II) sulfate, CuSO4 is greenish blue Copper compounds {{Chem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thallium Hydride
Thallane (systematically named trihydridothallium) is an inorganic compound with the empirical chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ... . It has not yet been obtained in bulk, hence its bulk properties remain unknown. However, molecular thallane has been isolated in solid gas matrices. Thallane is mainly produced for academic purposes. It is the simplest thallanes. Thallium is the heaviest member of the Group 13 metals; the stability of group 13 hydrides decreases with increasing periodic number. This is commonly attributed to poor overlap of the metal valence orbitals with that of the 1s orbital of Hydrogen. Despite encouraging early reports, it is unlikely that a thallane species has been isolated. Thallanes have been observed only in matrix isolation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury(II) Hydride
Mercury(II) hydride (systematically named mercurane(2) and dihydridomercury) is an inorganic compound with the chemical formula (also written as ). It is both thermodynamically and kinetically unstable at ambient temperature, and as such, little is known about its bulk properties. However, it known as a white, crystalline solid, which is kinetically stable at temperatures below , which was synthesised for the first time in 1951. Mercury(II) hydride is the second simplest mercury hydride (after mercury(I) hydride). Due to its instability, it has no practical industrial uses. However, in analytical chemistry, mercury(II) hydride is fundamental to certain forms of spectrometric techniques used to determine mercury content. In addition, it is investigated for its effect on high sensitivity isotope-ratio mass spectrometry methods that involve mercury, such as MC-ICP-MS, when used to compare thallium to mercury. Properties Structure In solid mercury(II) hydride, the HgH2 molecu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
