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Organocobalt
Organocobalt chemistry is the chemistry of organometallic compounds containing a carbon to cobalt chemical bond. Organocobalt compounds are involved in several organic reactions and the important biomolecule vitamin B12 has a cobalt-carbon bond. Many organocobalt compounds exhibit useful catalytic properties, the preeminent example being dicobalt octacarbonyl. Alkyl complexes Most fundamental are the cobalt complexes with only alkyl ligands. Examples include Co(4-norbornyl)4 and its cation. Alkylcobalt is represented by vitamin B12 and related enzymes. In methylcobalamin the ligand is a methyl group, which is electrophilic. in vitamin B12, the alkyl ligand is an adenosyl group. Related to vitamin B12 are cobalt porphyrins, dimethylglyoximates, and related complexes of Schiff base ligands. These synthetic compounds also form alkyl derivatives that undergo diverse reactions reminiscent of the biological processes. The weak cobalt(III)-carbon bond in vitamin B12 analogues c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cobalamin Skeletal
Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, in both fatty acid and amino acid metabolism. It is important in the normal functioning of the nervous system via its role in the synthesis of myelin, and in the circulatory system in the maturation of red blood cells in the bone marrow. Plants do not need cobalamin and carry out the reactions with enzymes that are not dependent on it. Vitamin B12 is the most chemically complex of all vitamins, and for humans, the only vitamin that must be sourced from animal-derived foods or from supplements. Only some archaea and bacteria can synthesize vitamin B12. Most people in developed countries get enough B12 from the consumption of meat or foods with animal sources. Foods containing vitamin B12 include meat, clams, liver, fish, poultry, eggs, and dairy products. Many breakfast cereals are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicobalt Octacarbonyl
Dicobalt octacarbonyl is an organocobalt compound with composition . This metal carbonyl is used as a reagent and catalyst in organometallic chemistry and organic synthesis, and is central to much known organocobalt chemistry. It is the parent member of a family of hydroformylation catalysts. Each molecule consists of two cobalt atoms bound to eight carbon monoxide ligands, although multiple structural isomers are known. Some of the carbonyl ligands are labile. Synthesis, structure, properties Dicobalt octacarbonyl an orange-colored, pyrophoric solid. It is synthesised by the high pressure carbonylation of cobalt(II) salts: : The preparation is often carried out in the presence of cyanide, converting the cobalt(II) salt into a hexacyanocobaltate(II) complex that reacts with carbon monoxide to yield . Acidification produces cobalt tetracarbonyl hydride, , which degrades near room temperature to dicobalt octacarbonyl and hydrogen. It can also be prepared by heating cobalt metal t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cobalt Mediated Radical Polymerization
Cobalt based catalysts, when used in radical polymerization, have several main advantages especially in slowing down the reaction rate, allowing for the synthesis of polymers with peculiar properties. As starting the reaction does need a real radical initiator, the cobalt species is not the only used catalyst, it is a mediator. For this reason this type of reaction is referred to as cobalt mediated radical polymerization. Introduction About half of all commercial polymers are produced by radical polymerization. Radical polymerization (RP) reactions have several advantageous properties: *A wide variety of monomers can be polymerized. *RP reactions are tolerant to various functional groups. *RP reactions allow a large temperature range of operation (–100 to >200 °C). *RP reactions are generally compatibility with several reactions conditions (bulk, solution, (mini)emulsion and suspension). *RP reactions allow a relatively simple reactor set-up, and are hence costs effectiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylidynetricobaltnonacarbonyl
Methylidynetricobaltnonacarbonyl is the organocobalt compound with the formula HCCo3(CO)9. It is a metal carbonyl cluster that contains the methylidyne ligand. The compound has C3v point group symmetry. It is a purple, air-stable solid that is soluble in some organic solvents, but not in water. The compound is prepared by the reaction of dicobalt octacarbonyl with bromoform. Much of the cobalt(0) is consumed in the formation of cobalt(II) bromide. An idealized equation for the synthesis is: :9 Co2(CO)8 + 4 CHBr3 → 4 HCCo3(CO)9 + 36 CO + 6 CoBr2 Many analogues are known, including the benzylidyne, arsinidyne, and chloromethylidyne derivatives, respectively , , and . The potential of some analogues as catalysts for hydroformylation – including with acylidyne and arylidyne moieties – has been investigated. The structure has been analyzed by X-ray crystallography. The Co-Co distances are near 2.48 Å in length. The compound is structurally related to tetr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylcobalamin
Methylcobalamin (mecobalamin, MeCbl, or MeB) is a cobalamin, a form of vitamin B. It differs from cyanocobalamin in that the cyano group at the cobalt is replaced with a methyl group. Methylcobalamin features an octahedral cobalt(III) centre and can be obtained as bright red crystals. From the perspective of coordination chemistry, methylcobalamin is notable as a rare example of a compound that contains metal–alkyl bonds. Nickel–methyl intermediates have been proposed for the final step of methanogenesis. Methylcobalamin is equivalent physiologically to vitamin B, and can be used to prevent or treat pathology arising from a lack of vitamin B intake ( vitamin B12 deficiency). Methylcobalamin is also used in the treatment of peripheral neuropathy, diabetic neuropathy, and as a preliminary treatment for amyotrophic lateral sclerosis. Methylcobalamin that is ingested is not used directly as a cofactor, but is first converted by MMACHC into cob(II)alamin. Cob(II)alamin is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicobalt Octacarbonyl
Dicobalt octacarbonyl is an organocobalt compound with composition . This metal carbonyl is used as a reagent and catalyst in organometallic chemistry and organic synthesis, and is central to much known organocobalt chemistry. It is the parent member of a family of hydroformylation catalysts. Each molecule consists of two cobalt atoms bound to eight carbon monoxide ligands, although multiple structural isomers are known. Some of the carbonyl ligands are labile. Synthesis, structure, properties Dicobalt octacarbonyl an orange-colored, pyrophoric solid. It is synthesised by the high pressure carbonylation of cobalt(II) salts: : The preparation is often carried out in the presence of cyanide, converting the cobalt(II) salt into a hexacyanocobaltate(II) complex that reacts with carbon monoxide to yield . Acidification produces cobalt tetracarbonyl hydride, , which degrades near room temperature to dicobalt octacarbonyl and hydrogen. It can also be prepared by heating cobalt metal t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vitamin B12
Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, in both fatty acid and amino acid metabolism. It is important in the normal functioning of the nervous system via its role in the synthesis of myelin, and in the circulatory system in the maturation of red blood cells in the bone marrow. Plants do not need cobalamin and carry out the reactions with enzymes that are not dependent on it. Vitamin B12 is the most chemically complex of all vitamins, and for humans, the only vitamin that must be sourced from animal-derived foods or from supplements. Only some archaea and bacteria can synthesize vitamin B12. Most people in developed countries get enough B12 from the consumption of meat or foods with animal sources. Foods containing vitamin B12 include meat, clams, liver, fish, poultry, eggs, and dairy products. Many breakfast cereals are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cobalt
Cobalt is a chemical element with the symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal. Cobalt-based blue pigments ( cobalt blue) have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was for a long time thought to be due to the known metal bismuth. Miners had long used the name ''kobold ore'' (German for ''goblin ore'') for some of the blue-pigment-producing minerals; they were so named because they were poor in known metals, and gave poisonous arsenic-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the ''kobold''. Today, some cobalt is produced specifically from one of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cobaltocene
Cobaltocene, known also as bis(cyclopentadienyl)cobalt(II) or even "bis Cp cobalt", is an organocobalt compound with the formula Co(C5H5)2. It is a dark purple solid that sublimes readily slightly above room temperature. Cobaltocene was discovered shortly after ferrocene, the first metallocene. Due to the ease with which it reacts with oxygen, the compound must be handled and stored using air-free techniques. Synthesis Cobaltocene is prepared by the reaction of sodium cyclopentadienide (NaC5H5) with anhydrous cobalt(II) chloride in THF solution. Sodium chloride is cogenerated, and the organometallic product is usually purified by vacuum sublimation. Structure and bonding In Co(C5H5)2 the Co centre is "sandwiched" between two cyclopentadienyl (Cp) rings. The Co–C bond lengths are about 2.1 Å, slightly longer than the Fe–C bond in ferrocene. Co(C5H5)2 belongs to a group of organometallic compounds called metallocenes or sandwich compounds. Cobaltocene has 19 valence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandwich Compound
In organometallic chemistry, a sandwich compound is a chemical compound featuring a metal bound by haptic, covalent bonds to two arene (ring) ligands. The arenes have the formula , substituted derivatives (for example ) and heterocyclic derivatives (for example ). Because the metal is usually situated between the two rings, it is said to be "sandwiched". A special class of sandwich complexes are the metallocenes. The term ''sandwich compound'' was introduced in organometallic nomenclature in 1956 in a report by J. D. Dunitz, L. E. Orgel and R. A. Rich, who confirmed the structure of ferrocene by X-ray crystallography. The correct structure, in which the molecule features an iron atom ''sandwiched'' between two parallel cyclopentadienyl rings, had been proposed several years previously by Robert Burns Woodward and, separately, by Ernst Otto Fischer. The structure helped explain puzzles about ferrocene's conformers. This result further demonstrated the power o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Progress In Polymer Science
''Progress in Polymer Science'' is a peer-reviewed scientific journal publishing review articles on topics broadly related to polymer chemistry. The 2021 impact factor of this journal was 31.281, ranking it the highest in the subject category "Polymer Science". The journal is available since 1967. Currently it is edited by Editor-in-Chief Jean-Francois Lutz and Senior Editors Michael Bockstaller and Chuanbing Tang. Honorary Editors-in-Chief include Krzysztof "Kris" Matyjaszewski and Guy C. Berry from Carnegie Mellon University Carnegie Mellon University (CMU) is a private research university in Pittsburgh, Pennsylvania. One of its predecessors was established in 1900 by Andrew Carnegie as the Carnegie Technical Schools; it became the Carnegie Institute of Technology .... References {{reflist Chemistry journals Materials science journals English-language journals Elsevier academic journals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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