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Triiron Dodecacarbonyl
Triiron dodecarbonyl is the organoiron compound with the formula Fe3(CO)12. It is a dark green solid that sublimes under vacuum. It is soluble in nonpolar organic solvents to give intensely green solutions. Most low-nuclearity clusters are pale yellow or orange. Hot solutions of Fe3(CO)12 decompose to an iron mirror, which can be pyrophoric in air.The solid decomposes slowly in air, and thus samples are typically stored cold under an inert atmosphere. It is a more reactive source of iron(0) than iron pentacarbonyl. Synthesis It was one of the first metal carbonyl clusters synthesized. It was occasionally obtained from the thermolysis of Fe(CO)5: :3 Fe(CO)5 → Fe3(CO)12 + 3 CO Traces of the compound are easily detected because of its characteristic deep green colour. UV-photolysis of Fe(CO)5 produces Fe2(CO)9, not Fe3(CO)12. The usual synthesis of Fe3(CO)12 starts with the reaction of Fe(CO)5 with base: :3 Fe(CO)5 + (C2H5)3N + H2O → C2H5)3NHHFe3(CO)11] + 3 CO + CO2 follow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triruthenium Dodecacarbonyl
Triruthenium dodecacarbonyl is the chemical compound with the formula Ru3(CO)12. Classified as metal carbonyl cluster, it is a dark orange-colored solid that is soluble in nonpolar organic solvents. The compound serves as a precursor to other organoruthenium compounds. Structure and synthesis The cluster has ''D3h'' symmetry, consisting of an equilateral triangle of Ru atoms, each of which bears two axial and two equatorial CO ligands. Os3(CO)12 has the same structure, whereas Fe3(CO)12 is different, with two bridging CO ligands, resulting in C2v symmetry. Ru3(CO)12 is prepared by treating solutions of ruthenium trichloride with carbon monoxide in the presence of a base. Dichlororuthenium tricarbonyl dimer is an intermediate. The stoichiometry of the reaction is uncertain, one possibility being the following: :6 RuCl3 + 33 CO + 18 CH3OH → 2 Ru3(CO)12 + 9 CO(OCH3)2 + 18 HCl Reactions The chemical properties of Ru3(CO)12 have been widely studied, and the cluster ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Walter Hieber
Walter Hieber (18 December 1895 – 29 November 1976) was an inorganic chemist, known as the father of metal carbonyl chemistry. He was born 18 December 1895 and died 29 November 1976. Hieber's father was Johannes Hieber, an influential evangelical minister and politician. Hieber was educated at Tübingen, Würzburg, and Heidelberg. In 1935 he was appointed Director of the Inorganic Chemical Institute at the Technical University in Münich. Among his numerous research findings, Hieber prepared the first metal carbonyl hydrides such as H2Fe(CO)4 and HMn(CO)5. He discovered that metal carbonyls undergo nucleophilic attack by hydroxide, the “Hieber base reaction.” He and his students discovered several metal carbonyl compounds such as Re2(CO)10 and Os3(CO)12 He pioneered the development of metal carbonyl sulfides.Hieber, W. and Scharfenberg, C., "Einwirkung organischer Schwefelverbindungen auf die Carbonyls des Eisens", Chemische Berichte, 1940, volume 73, pages 1012 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disproportionation
In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can be applied to any desymmetrizing reaction of the following type, regardless of whether it is a redox or some other type of process: :2A -> A' + A'' Examples *Mercury(I) chloride disproportionates upon UV-irradiation: :Hg2Cl2 → Hg + HgCl2 *Phosphorous acid disproportionates upon heating to give phosphoric acid and phosphine: :4 → 3 H3PO4 + PH3 *Desymmetrizing reactions are sometimes referred to as disproportionation, as illustrated by the thermal degradation of bicarbonate: :2 → + H2CO3 :The oxidation numbers remain constant in this acid-base reaction. This process is also called autoionization. *Another variant on disproportionation is radical disproportionation, in which two radicals form an alkene and an alkane. : Reverse r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Carbido Complex
A metal carbido complex is a coordination complex that contains a carbon atom as a ligand. Carbido complexes are a molecular subclass of carbides, which are prevalent. Carbido complexes represent models for intermediates in Fischer–Tropsch synthesis and related catalytic processes. They are also used as precursors for the synthesis of more complicated carbides. They are analogous to metal nitrido complexes. Carbido clusters Most molecular carbido complexes are clusters, usually featuring carbide as a six-fold bridging ligand. Examples include , and . The iron carbonyl carbides exist not only in the encapsulated carbon () but also with exposed carbon centres as in and . Clusters without CO ligands are also known. Doubly bridging carbide ligands Bridging carbido ligands can be subdivided into three classes: *cumulenic , *metallocarbyne , and *polar covalent . Cumulenic compounds generally bridge two metal atoms of the same element and are symmetrical. However, there are except ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triphenylphosphine
Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether. Preparation and structure Triphenylphosphine can be prepared in the laboratory by treatment of phosphorus trichloride with phenylmagnesium bromide or phenyllithium. The industrial synthesis involves the reaction between phosphorus trichloride, chlorobenzene, and sodium: :PCl3 + 3 PhCl + 6 Na → PPh3 + 6 NaCl Triphenylphosphine crystallizes in triclinic and monoclinic modification. In both cases, the molecule adopts a pyramidal structure with propeller-like arrangement of the three phenyl groups. Principal reactions with chalcogens, halogens, and acids Oxidation Triphenylphosphine undergoes slow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diborane
Diborane(6), generally known as diborane, is the chemical compound with the formula B2H6. It is a toxic, colorless, and pyrophoric gas with a repulsively sweet odor. Diborane is a key boron compound with a variety of applications. It has attracted wide attention for its electronic structure. Several of its derivatives are useful reagents. Structure and bonding The structure of diborane has D2h symmetry. Four hydrides are terminal, while two bridge between the boron centers. The lengths of the B–Hbridge bonds and the B–Hterminal bonds are 1.33 and 1.19 Å respectively. This difference in bond lengths reflects the difference in their strengths, the B–Hbridge bonds being relatively weaker. The weakness of the B–Hbridge compared to B–Hterminal bonds is indicated by their vibrational signatures in the infrared spectrum, being ≈2100 and 2500 cm−1 respectively. The model determined by molecular orbital theory describes the bonds between boron and the termina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopropane
Cyclopropane is the cycloalkane with the molecular formula (CH2)3, consisting of three methylene groups (CH2) linked to each other to form a ring. The small size of the ring creates substantial ring strain in the structure. Cyclopropane itself is mainly of theoretical interest but many of its derivatives are of commercial or biological significance. History Cyclopropane was discovered in 1881 by August Freund, who also proposed the correct structure for the substance in his first paper. Freund treated 1,3-dibromopropane with sodium, causing an intramolecular Wurtz reaction leading directly to cyclopropane. The yield of the reaction was improved by Gustavson in 1887 with the use of zinc instead of sodium. Cyclopropane had no commercial application until Henderson and Lucas discovered its anaesthetic properties in 1929; industrial production had begun by 1936. In modern anaesthetic practice, it has been superseded by other agents. Anaesthesia Cyclopropane was introduced into cli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylene Radical
Methylene (systematically named methylidene and dihydridocarbon; also called carbene) is an organic compound with the chemical formula (also written ). It is a colourless gas that fluoresces in the mid-infrared range, and only persists in dilution, or as an adduct. Methylene is the simplest carbene.Roald Hoffman (2005), ''Molecular Orbitals of Transition Metal Complexes''. Oxford. It is usually detected only at very low temperatures, or as a short-lived intermediate in chemical reactions. W. B. DeMore and S. W. Benson (1964), Preparation, properties, and reactivity of methylene'. In ''Advances in Photochemistry'', John Wiley & Sons, 453 pages. Nomenclature The trivial name ''carbene'' is the preferred IUPAC name. The systematic names ''methylidene'' and ''dihydridocarbon'', valid IUPAC names, are constructed according to the substitutive and additive nomenclatures, respectively. ''Methylidene'' is viewed as methane with two hydrogen atoms removed. By default, this name ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluxional Molecule
In chemistry and molecular physics, fluxional (or non-rigid) molecules are molecules that undergo dynamics such that some or all of their atoms interchange between symmetry-equivalent positions. Because virtually all molecules are fluxional in some respects, e.g. bond rotations in most organic compounds, the term fluxional depends on the context and the method used to assess the dynamics. Often, a molecule is considered fluxional if its spectroscopic signature exhibits line-broadening (beyond that dictated by the Heisenberg uncertainty principle) due to chemical exchange. In some cases, where the rates are slow, fluxionality is not detected spectroscopically, but by isotopic labeling and other methods. Spectroscopic studies Many organometallic compounds exhibit fluxionality. Fluxionality is however pervasive. NMR spectroscopy Temperature dependent changes in the NMR spectra result from dynamics associated with the fluxional molecules when those dynamics proceed at rates comparabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triosmium Dodecacarbonyl
Triosmium dodecacarbonyl is a chemical compound with the formula Os3(CO)12. This yellow-colored metal carbonyl cluster is an important precursor to organo-osmium compounds. Many of the advances in cluster chemistry have arisen from studies on derivatives of Os3(CO)12 and its lighter analogue Ru3(CO)12. Structure and synthesis The cluster has D3h symmetry, consisting of an equilateral triangle of Os atoms, each of which bears two axial and two equatorial CO ligands. Each of the three osmium centers has an octahederal structure with four CO ligands and the other two osmium atoms. The Os–Os bond distance is 2.88 Â (288 pm). Ru3(CO)12 has the same structure, whereas Fe3(CO)12 is different, with two bridging CO ligands resulting in C2v symmetry. Os3(CO)12 is prepared by the direct reaction of OsO4 with carbon monoxide at 175 °C under high pressures: : 3 OsO4 + 24 CO → Os3(CO)12 + 12 CO2 The yield is nearly quantitative. Reactions The chemical properties of O ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triruthenium Dodecacarbonyl
Triruthenium dodecacarbonyl is the chemical compound with the formula Ru3(CO)12. Classified as metal carbonyl cluster, it is a dark orange-colored solid that is soluble in nonpolar organic solvents. The compound serves as a precursor to other organoruthenium compounds. Structure and synthesis The cluster has ''D3h'' symmetry, consisting of an equilateral triangle of Ru atoms, each of which bears two axial and two equatorial CO ligands. Os3(CO)12 has the same structure, whereas Fe3(CO)12 is different, with two bridging CO ligands, resulting in C2v symmetry. Ru3(CO)12 is prepared by treating solutions of ruthenium trichloride with carbon monoxide in the presence of a base. Dichlororuthenium tricarbonyl dimer is an intermediate. The stoichiometry of the reaction is uncertain, one possibility being the following: :6 RuCl3 + 33 CO + 18 CH3OH → 2 Ru3(CO)12 + 9 CO(OCH3)2 + 18 HCl Reactions The chemical properties of Ru3(CO)12 have been widely studied, and the cluster ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Symmetry
Molecular symmetry in chemistry describes the symmetry present in molecules and the classification of these molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can be used to predict or explain many of a molecule's chemical properties, such as whether or not it has a dipole moment, as well as its allowed spectroscopic transitions. To do this it is necessary to use group theory. This involves classifying the states of the molecule using the irreducible representations from the character table of the symmetry group of the molecule. Symmetry is useful in the study of molecular orbitals, with applications to the Hückel method, to ligand field theory, and to the Woodward-Hoffmann rules. Many university level textbooks on physical chemistry, quantum chemistry, spectroscopy and inorganic chemistry discuss symmetry. Another framework on a larger scale is the use of crystal systems to describe crystallographic symmetry in bulk materia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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