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Organomolybdenum
Organomolybdenum chemistry is the chemistry of chemical compounds with Mo-C bonds. The heavier group 6 elements molybdenum and tungsten form organometallic compounds similar to those in organochromium chemistry but higher oxidation states tend to be more common. Mo(0) and more reduced states Molybdenum hexacarbonyl is the precursor to many substituted derivatives. It reacts with organolithium reagents to give anionic acyls which can be O-alkylated to give Fischer carbenes. 144px, Structure of (mesitylene)molybdenum tricarbonyl. Mo(CO)6 reacts with arenes to give piano-stool complexes such as (mesitylene)molybdenum tricarbonyl. Cycloheptatrienemolybdenum tricarbonyl, which is related to (arene)Mo(CO)3, reacts with trityl salts to give the cycloheptatrienyl complex: :(C7H8)Mo(CO)3 + (C6H5)3C+ → C7H7)Mo(CO)3sup>+ + (C6H5)3CH file:CHTMo(CO)3.png, 144px, Structure of Cycloheptatrienemolybdenum tricarbonyl. Reduction of Mo(CO)6 gives [Mo(CO)5]2− which is formally Mo( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cp2MoH2
Molybdocene dihydride is the organomolybdenum compound with the formula ( η5-C5H5)2MoH2. Commonly abbreviated as Cp2MoH2, it is a yellow air-sensitive solid that dissolves in some organic solvents. The compound is prepared by combining molybdenum pentachloride, sodium cyclopentadienide, and sodium borohydride. The dihydride converts to molybdocene dichloride upon treatment with chloroform Chloroform, or trichloromethane, is an organic compound with chemical formula, formula Carbon, CHydrogen, HChlorine, Cl3 and a common organic solvent. It is a colorless, strong-smelling, dense liquid produced on a large scale as a precursor to .... The compound adopts a "clamshell" structure where the Cp rings are not parallel.K. Prout, T. S. Cameron, R. A. Forder, and in parts S. R. Critchley, B. Denton and G. V. Rees "The crystal and molecular structures of bent bis-π-cyclopentadienyl-metal complexes: (a) bis-π-cyclopentadienyldibromorhenium(V) tetrafluoroborate, (b) bis-π-cyclopent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molybdocene Dihydride
Molybdocene dihydride is the organomolybdenum compound with the formula ( η5-C5H5)2MoH2. Commonly abbreviated as Cp2MoH2, it is a yellow air-sensitive solid that dissolves in some organic solvents. The compound is prepared by combining molybdenum pentachloride, sodium cyclopentadienide, and sodium borohydride. The dihydride converts to molybdocene dichloride upon treatment with chloroform Chloroform, or trichloromethane, is an organic compound with chemical formula, formula Carbon, CHydrogen, HChlorine, Cl3 and a common organic solvent. It is a colorless, strong-smelling, dense liquid produced on a large scale as a precursor to .... The compound adopts a "clamshell" structure where the Cp rings are not parallel.K. Prout, T. S. Cameron, R. A. Forder, and in parts S. R. Critchley, B. Denton and G. V. Rees "The crystal and molecular structures of bent bis-π-cyclopentadienyl-metal complexes: (a) bis-π-cyclopentadienyldibromorhenium(V) tetrafluoroborate, (b) bis-π-cyclopent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molybdocene Dichloride
Molybdocene dichloride is the organomolybdenum compound with the formula ( η5-C5H5)2MoCl2 and IUPAC name dichlorobis(η5-cyclopentadienyl)molybdenum(IV), and is commonly abbreviated as Cp2MoCl2. It is a brownish-green air- and moisture-sensitive powder. In the research laboratory, it is used to prepare many derivatives. Preparation and structure The compound is prepared from molybdocene dihydride by treatment with chloroform: :(C5H5)2MoH2 + 2 CHCl3 → (C5H5)2MoCl2 + 2 CH2Cl2 The compound adopts a "clamshell" structure where the Cp rings are not parallel, the average Cp(centroid)-M-Cp angle being 130.6°. The two chloride ligands are cis, the Cl-Mo-Cl angle of 82° being narrower than in niobocene dichloride (85.6°), which in turn is less than in zirconacene dichloride Zirconocene dichloride is an organozirconium compound composed of a zirconium central atom, with two cyclopentadienyl and two chloro ligands. It is a colourless diamagnetic solid that is somewhat stable in air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tungsten
Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite and wolframite, the latter lending the element its alternate name. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all known elements barring carbon (which sublimes at normal pressure), melting at . It also has the highest boiling point, at . Its density is , comparable with that of uranium and gold, and much higher (about 1.7 times) than that of lead. Polycrystalline tungsten is an intrinsically brittle and hard material (under standard conditions, when uncombined), making it difficult to work. However, pure single-crystalline tungsten is more ductile and can be cut with a hard-steel hacksaw. Tungsten occurs in many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molybdenum Hexacarbonyl
Molybdenum hexacarbonyl (also called molybdenum carbonyl) is the chemical compound with the formula Mo(CO)6. This colorless solid, like its chromium and tungsten analogues, is noteworthy as a volatile, air-stable derivative of a metal in its zero oxidation state. Structure and properties Mo(CO)6 adopts an octahedral geometry consisting of six rod-like CO ligands radiating from the central Mo atom. A recurring minor debate in some chemical circles concerns the definition of an "organometallic" compound. Usually, organometallic indicates the presence of a metal directly bonded via a M–C bond to an organic fragment, which must in turn have a C–H bond. Mo(CO)6 is prepared by the reduction of molybdenum chlorides or oxides under a pressure of carbon monoxide, although it would be unusual to prepare this inexpensive compound in the laboratory. The compound is somewhat air-stable and sparingly soluble in nonpolar organic solvents. Occurrence Mo(CO)6 has been detected in landfil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
(Mesitylene)molybdenum Tricarbonyl
(Mesitylene)molybdenum tricarbonyl is an organomolybdenum compound derived from the aromatic compound mesitylene (1,3,5-trimethylbenzene) and molybdenum carbonyl. It exists as pale yellow crystals, which are soluble in organic solvents but decompose when in solution. It has been examined as a catalyst and reagent. Synthesis (Mesitylene)molybdenum tricarbonyl arises from the reaction of molybdenum hexacarbonyl with hot mesitylene: :Mo(CO) + (CH)CH → Mo(CO) CH)CH+ 3 CO It can also be synthesized, with good yields by displacement of pyridine ligands of the trispyridine complex Mo(CO)(pyridine) in the presence of Lewis acids. This reaction proceeds at lower temperatures of the compound than the direct method :PyMo(CO) + (CH)CH + 3BF·O(CH) → CH)CHo(CO) + 3PyBF Structure and properties The mesitylene group is bonded to the molybdenum centre through delocalized π - electron ring. The aromaticity of the ligand is indicated by its ability to undergo Friedel-Crafts reactions, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycloheptatrienemolybdenum Tricarbonyl
Cycloheptatrienemolybdenum tricarbonyl is the organomolybdenum compound with the formula (C7H8)Mo(CO)3. It is a red-orange solid that is soluble in nonpolar organic solvents. The compound has no practical value but is a prototypical complex of cycloheptatriene. Synthesis, structure, and reactions The compound is prepared by thermal reaction of the triene with molybdenum hexacarbonyl: :C7H8 + Mo(CO)6 → (C7H8)Mo(CO)3 + 3 CO The compound is a piano stool complex, consisting of Mo(CO)3 bound to six carbon centers of the triene. The methylene group projects from the plane of the six coordinated carbon atoms. The compound reacts with trityl Triphenylmethane, or triphenyl methane, is the hydrocarbon with the formula (C6H5)3CH. This colorless solid is soluble in nonpolar organic solvents and not in water. Triphenylmethane is the basic skeleton of many synthetic dyes called triarylmetha ... salts to give the cycloheptatrienyl complex: M. L. H. Green, D. K. P. Ng "Cyclohepta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopentadienylmolybdenum Tricarbonyl Dimer
Cyclopentadienylmolybdenum tricarbonyl dimer is the chemical compound with the formula Cp2Mo2(CO)6, where Cp is C5H5. A dark red solid, it has been the subject of much research although it has no practical uses. Structure and synthesis The molecule exists in two rotamers, gauche and anti. The six CO ligands are terminal and the Mo-Mo bond distance is 3.2325 Å. The compound is prepared by treatment of molybdenum hexacarbonyl with sodium cyclopentadienide followed by oxidation of the resulting NaMo(CO)3(C5H5). Other methods have been developed starting with Mo(CO)3(CH3CN)3 instead of Mo(CO)6. Reactions Thermolysis of this compound in hot solution of diglyme (bis(2-methoxyethyl)ether) results in decarbonylation, giving the tetracarbonyl, which has a formal triple bond between the Mo centers (''d''MoMo = 2.448 Å):Cotton, F. A.; Walton, R. A. "Multiple Bonds Between Metal Atoms" Oxford (Oxford): 1993, p 564ff. . :(C5H5)2Mo2(CO)6 → (C5H5)2Mo2(CO)4 + 2 CO The resulting cyclopenta ... [...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] |
Ansa Metallocene
An ''ansa''-metallocene is a type of organometallic compound containing two cyclopentadienyl ligands that are linked by a bridging group such that both cyclopentadienyl groups are bound to the same metal. The link prevents rotation of the cyclopentadienyl ligand and often modifies the structure and reactivity of the metal center. Some ansa-metallocenes are active in Ziegler-Natta catalysis, although none are used commercially. The term ''ansa''-metallocene (ansa being Greek for "handle") was coined by Lüttringhaus and Kullick to describe alkylidene-bridged ferrocenes, which were developed in the 1950s. Often ''ansa''-metallocenes are described in terms of the angle defined by the two Cp rings. In titanocene dichloride, this angle is 58.5° whereas in the ''ansa''-titanocene Me2Si(C5H4)2TiCl2 the angle is 51.2°. The prototypical linker groups are of the type (CH2)n where n = 1, 2, and 3. More easily installed are linker groups consisting of heteroatoms, e.g. (CH3)2Si. One ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkoxide
In chemistry, an alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. They are written as , where R is the organic substituent. Alkoxides are strong bases and, when R is not bulky, good nucleophiles and good ligands. Alkoxides, although generally not stable in protic solvents such as water, occur widely as intermediates in various reactions, including the Williamson ether synthesis. Transition metal alkoxides are widely used for coatings and as catalysts. Enolates are unsaturated alkoxides derived by deprotonation of a bond adjacent to a ketone or aldehyde. The nucleophilic center for simple alkoxides is located on the oxygen, whereas the nucleophilic site on enolates is delocalized onto both carbon and oxygen sites. Ynolates are also unsaturated alkoxides derived from acetylenic alcohols. Phenoxides are close relatives of the alkoxides, in which the alkyl group is replaced by a derivative of be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
