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Transition Metal Imido Complex
In coordination chemistry and organometallic chemistry, transition metal imido complexes is a coordination compound containing an imido ligand. Imido ligands can be terminal or bridging ligands. The parent imido ligand has the formula NH, but most imido ligands have alkyl or aryl groups in place of H. The imido ligand is generally viewed as a dianion, akin to oxide. Structural classes Complexes with terminal imido ligands In some terminal imido complexes, the M=N−C angle is 180° but often the angle is decidedly bent. Complexes of the type M=NH are assumed to be intermediates in nitrogen fixation by synthetic catalysts.Nugent, W. A.; Mayer, J. M., "Metal-Ligand Multiple Bonds," J. Wiley: New York, 1988. 220px, Typical Schrock-style olefin metathesis catalyst features imides as spectator ligands.">spectator_ligand.html" ;"title="olefin metathesis catalyst features imides as spectator ligand">olefin metathesis catalyst features imides as spectator ligands. Complexes with bridg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molybdenum Dichloride Dioxide
Molybdenum dichloride dioxide is the inorganic compound with the formula MoO2Cl2. It is a yellow diamagnetic solid that is used as a precursor to other molybdenum compounds. Molybdenum dichloride dioxide is one of several oxychlorides of molybdenum. Structure Gaseous molybdenum dichloride dioxide is a monomer, but upon condensation, it polymerizes to give a coordination polymer of uncertain structure. Preparation The compound is most easily prepared by treatment molybdenum trioxide with concentrated hydrochloric acid: :MoO3 + 2 HCl → MoO2Cl2 + H2O MoO2Cl2 can also be prepared from MoOCl4: :MoOCl4 + O(Si(CH3)3)2 → MoO2Cl2 + 2 ClSi(CH3)3 It is also prepared by chlorination of molybdenum dioxide: :MoO2 + Cl2 → MoO2Cl2 It is also prepared by chlorination of molybdenum trixoide: :MoO3 + Cl2 → MoO2Cl2 Reactions Many bisadducts are known of the type MoO2Cl2(ether)2. These octahedral molecular complexes are soluble in organic solvents. With bulky anili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammoxidation
In organic chemistry, ammoxidation is a process for the production of nitriles () using ammonia () and oxygen (). It is sometimes called the SOHIO process, acknowledging that ammoxidation was developed at Standard Oil of Ohio. The usual substrates are alkenes. Several million tons of acrylonitrile are produced in this way annually: :CH3CH=CH2 + 3/2 O2 + NH3 -> N#CCH=CH2 + 3 H2O Scope Ammoxidation of alkenes exploits the weak C-H bonds that are located in the allylic position of unsaturated hydrocarbons. Benzylic C-H bonds are also susceptible to ammoxidation, reflecting the weakness of their C-H bonds. Benzonitrile is produced from toluene, and phthalonitriles are produced from xylenes. The reaction represents a partial oxidation. Many byproducts are generated, but the feedstocks are often simple, which compensates for these losses. Additionally, some byproducts are useful or recyclable. For the production of acrylonitrile, byproducts include hydrogen cyanide, acrole ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Metal Nitrido Complex
Metal nitrido complexes are coordination compounds and metal clusters that contain an atom of nitrogen bound only to transition metals. These compounds are ''molecular'', i.e. discrete in contrast to the polymeric, dense nitride materials that are useful in materials science. The distinction between the molecular and solid-state polymers is not always very clear as illustrated by the materials Li6MoN4 and more condensed derivatives such as Na3MoN3. Transition metal nitrido complexes have attracted interest in part because it is assumed that nitrogen fixation proceeds via nitrido intermediates. Nitrido complexes have long been known, the first example being salts of sO3Nsup>−, described in the 19th century. Structural trends Mononuclear complexes feature terminal nitride ligands, typically with short M-N distances consistent with metal ligand multiple bonds. For example, in the anion in PPh4 oNCl4 the Mo-N distance is 163.7 pm. The occurrence of terminal nitrido ligands f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isocyanate
In organic chemistry, isocyanate is the functional group with the formula . Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyanates are manufactured for the production of polyurethanes, a class of polymers. Isocyanates should not be confused with cyanate esters and isocyanides, very different families of compounds. The cyanate (cyanate ester) functional group () is arranged differently from the isocyanate group (). Isocyanides have the connectivity , lacking the oxygen of the cyanate groups. Structure and bonding In terms of bonding, isocyanates are closely related to carbon dioxide (CO2) and carbodiimides (C(NR)2). The C−N=C=O unit that defines isocyanates is planar, and the N=C=O linkage is nearly linear. In phenyl isocyanate, the C=N and C=O distances are respectively 1.195 and 1.173 Å. The C-N=C angle is 134.9° and the N=C=O angle is 173.1°. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schrock Carbene
A transition metal carbene complex is an organometallic compound featuring a divalent organic ligand. The divalent organic ligand coordinated to the metal center is called a carbene. Carbene complexes for almost all transition metals have been reported. Many methods for synthesizing them and reactions utilizing them have been reported. The term carbene ligand is a formalism since many are not derived from carbenes and almost none exhibit the reactivity characteristic of carbenes. Described often as , they represent a class of organic ligands intermediate between alkyls and carbynes . They feature in some catalytic reactions, especially alkene metathesis, and are of value in the preparation of some fine chemicals. Classification Metal carbene complexes are often classified into two types. The Fischer carbenes named after Ernst Otto Fischer feature strong π-acceptors at the metal and being electrophilic at the carbene carbon atom. Schrock carbenes, named after Richard R. Schrock ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dimethoxyethane
Dimethoxyethane, also known as glyme, monoglyme, dimethyl glycol, ethylene glycol dimethyl ether, dimethyl cellosolve, and DME, is a colorless, aprotic, and liquid ether that is used as a solvent, especially in batteries. Dimethoxyethane is miscible with water. Production Monoglyme is produced industrially by the reaction of dimethylether with ethylene oxide: :CH3OCH3 + CH2CH2O → CH3OCH2CH2OCH3 Applications as solvent and ligand left, 144px, Structure of the coordination complex NbCl3(dimethoxyethane)(3-hexyne).{{cite journal , doi=10.1021/ja8100837, title=New Tantalum Ligand-Free Catalyst System for Highly Selective Trimerization of Ethylene Affording 1-Hexene: New Evidence of a Metallacycle Mechanism, year=2009, last1=Arteaga-Müller, first1=RocÃo, last2=Tsurugi, first2=Hayato, last3=Saito, first3=Teruhiko, last4=Yanagawa, first4=Masao, last5=Oda, first5=Seiji, last6=Mashima, first6=Kazushi, journal=Journal of the American Chemical Society, volume=131, issue=15, pages=5370â ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Oxo Complex
A transition metal oxo complex is a coordination complex containing an oxo ligand. Formally O2-, an oxo ligand can be bound to one or more metal centers, i.e. it can exist as a terminal or (most commonly) as bridging ligands (Fig. 1). Oxo ligands stabilize high oxidation states of a metal.Nugent, W. A., Mayer, J. M. "Metal-Ligand Multiple Bonds." John Wiley & Sons, New York, 1988. They are also found in several metalloproteins, for example in molybdenum cofactors and in many iron-containing enzymes. One of the earliest synthetic compounds to incorporate an oxo ligand is potassium ferrate (K2FeO4), which was likely prepared by Georg E. Stahl in 1702. Reactivity Olation and acid-base reactions A common reaction exhibited by metal-oxo compounds is olation, the condensation process that converts low molecular weight oxides to polymers with M-O-M linkages. Olation often begins with the deprotonation of a metal-hydroxo complex. It is the basis for mineralization and the precipita ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coordination Chemistry
A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many metal-containing compounds, especially those that include transition metals (elements like titanium that belong to the Periodic Table's d-block), are coordination complexes. Nomenclature and terminology Coordination complexes are so pervasive that their structures and reactions are described in many ways, sometimes confusingly. The atom within a ligand that is bonded to the central metal atom or ion is called the donor atom. In a typical complex, a metal ion is bonded to several donor atoms, which can be the same or different. A polydentate (multiple bonded) ligand is a molecule or ion that bonds to the central atom through several of the ligand's atoms; ligands with 2, 3, 4 or even 6 bonds to the central atom are common. These compl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrogen Fixation
Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atmospheric nitrogen is molecular dinitrogen, a relatively nonreactive molecule that is metabolically useless to all but a few microorganisms. Biological nitrogen fixation or ''diazotrophy'' is an important microbials mediated process that converts dinitrogen (N2) gas to ammonia (NH3) using the nitrogenase protein complex (Nif). Nitrogen fixation is essential to life because fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen-containing organic compounds, such as amino acids and proteins, nucleoside triphosphates and nucleic acids. As part of the nitrogen cycle, it is essential for agriculture and the manufacture of fertilizer. It is also, indirectly, relevant to the manufacture of all nitrogen chemical c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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