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Cyclopentadienylcobalt Dicarbonyl
Cyclopentadienylcobalt dicarbonyl is an organocobalt compound with formula (C5H5)Co(CO)2, abbreviated CpCo(CO)2. It is an example of a half-sandwich complex. It is a dark red air sensitive liquid. This compound features one cyclopentadienyl ring that is bound in an η5-manner and two carbonyl ligands. The compound is soluble in common organic solvents. Preparation CpCo(CO)2 was first reported in 1954 by Piper, Cotton, and Wilkinson who produced it by the reaction of cobalt carbonyl with cyclopentadiene. It is prepared commercially by the same method: : Co2(CO)8 + 2 C5H6 → 2 C5H5Co(CO)2 + H2 + 4 CO Alternatively, it is generated by the high pressure carbonylation of bis(cyclopentadienyl)cobalt (cobaltocene) at elevated temperature and pressures: :Co(C5H5)2 + 2 CO → C5H5Co(CO)2 + "C5H5" The compound is identified by strong bands in its IR spectrum at 2030 and 1960 cm−1. Reactions CpCo(CO)2 catalyzes the cyclotrimerization of alkynes. The catalytic cycle begins w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
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] |
Carbonyl Complexes
In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containing a carbonyl group is often referred to as a carbonyl compound. The term carbonyl can also refer to carbon monoxide as a ligand in an inorganic or organometallic complex (a metal carbonyl, e.g. nickel carbonyl). The remainder of this article concerns itself with the organic chemistry definition of carbonyl, where carbon and oxygen share a double bond. Carbonyl compounds In organic chemistry, a carbonyl group characterizes the following types of compounds: Other organic carbonyls are urea and the carbamates, the derivatives of acyl chlorides chloroformates and phosgene, carbonate esters, thioesters, lactones, lactams, hydroxamates, and isocyanates. Examples of inorganic carbonyl compounds are carbon dioxide and carbonyl sulfide. A sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopentadienyl Complexes
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Cyclopentadienyl can refer to *Cyclopentadienyl anion, or cyclopentadienide, **Cyclopentadienyl ligand *Cyclopentadienyl radical, • *Cyclopentadienyl cation, See also *Pentadienyl In organic chemistry, pentadienyl refers to the organic radical, anion, or cation with the formula , where ''z'' = 0, −1, +1, respectively. Organometallic chemistry In organometallic chemistry, the pentadienyl anion is a ligand, the acyclic ana ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentamethylcyclopentadienyl
1,2,3,4,5-Pentamethylcyclopentadiene is a cyclic diene with the formula C5Me5H (Me = CH3). 1,2,3,4,5-Pentamethylcyclopentadiene is the precursor to the ligand ''1,2,3,4,5-pentamethylcyclopentadienyl'', which is often denoted Cp* (C5Me5) and read as "C P star", the "star" signifying the five methyl groups radiating from the core of the ligand. In contrast to less-substituted cyclopentadiene derivatives, Cp*H is not prone to dimerization. Synthesis Pentamethylcyclopentadiene is commercially available. It was first prepared from tiglaldehyde via 2,3,4,5-tetramethylcyclopent-2-enone. Alternatively, 2-butenyllithium adds to ethyl acetate followed by acid-catalyzed dehydrocyclization: Organometallic derivatives Cp*H is a precursor to organometallic compounds containing the ligand, commonly called Cp*−. Some representative reactions leading to such Cp*–metal complexes follow: :Cp*H + C4H9Li → Cp*Li + C4H10 :Cp*Li + TiCl4 → Cp*TiCl3 + LiCl Some Cp* co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nitrile
In organic chemistry, a nitrile is any organic compound that has a functional group. The prefix ''cyano-'' is used interchangeably with the term ''nitrile'' in industrial literature. Nitriles are found in many useful compounds, including methyl cyanoacrylate, used in super glue, and nitrile rubber, a nitrile-containing polymer used in latex-free laboratory and medical gloves. Nitrile rubber is also widely used as automotive and other seals since it is resistant to fuels and oils. Organic compounds containing multiple nitrile groups are known as cyanocarbons. Inorganic compounds containing the group are not called nitriles, but cyanides instead. Though both nitriles and cyanides can be derived from cyanide salts, most nitriles are not nearly as toxic. Structure and basic properties The N−C−C geometry is linear in nitriles, reflecting the sp hybridization of the triply bonded carbon. The C−N distance is short at 1.16 Å, consistent with a triple bond. Nitriles a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a distinctive, unpleasant fish-like smell. Pyridine is colorless, but older or impure samples can appear yellow, due to the formation of extended, unsaturated polymeric chains, which show significant electrical conductivity. The pyridine ring occurs in many important compounds, including agrochemicals, pharmaceuticals, and vitamins. Historically, pyridine was produced from coal tar. As of 2016, it is synthesized on the scale of about 20,000 tons per year worldwide. Properties Physical properties The molecular electric dipole moment is 2.2 debyes. Pyridine is diamagnetic and has a diamagnetic susceptibility of −48.7 × 10−6 cm3·mol−1. The standard enthalpy of formation is 100.2 kJ·mol−1 in the liquid phase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal-alkyne Complex
In organometallic chemistry, a transition metal alkyne complex is a coordination compound containing one or more alkyne ligands. Such compounds are intermediates in many catalytic reactions that convert alkynes to other organic products, e.g. hydrogenation and trimerization. Synthesis Transition metal alkyne complexes are often formed by the displacement of labile ligands by the alkyne. For example, a variety of cobalt-alkyne complexes may be formed by reaction of the alkyne with dicobalt octacarbonyl. : Co2(CO)8 + R2C2 → Co2(C2R2)(CO)6 + 2 CO Many alkyne complexes are produced by reduction of metal halides: : Cp2TiCl2 + Mg + Me3SiC≡CSiMe3 → Cp2Ti CSiMe3)2+ MgCl2 Structure and bonding The coordination of alkynes to transition metals is similar to that of alkenes. The bonding is described by the Dewar–Chatt–Duncanson model. Upon complexation the C-C bond elongates and the alkynyl carbon bends away from 180º. For example, in the phenylpropyne complex Pt(PPh3)2(MeC2Ph), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alkyne Trimerisation
In organic chemistry, an alkyne trimerisation is a +2+2nbsp; cycloaddition reaction in which three alkyne units () react to form a benzene ring. The reaction requires a metal catalyst. The process is of historic interest as well as being applicable to organic synthesis. Being a cycloaddition reaction, it has high atom economy. Many variations have been developed, including cyclisation of mixtures of alkynes and alkenes as well as alkynes and nitriles. Mechanism and stereochemistry Trimerisation of acetylene to benzene is highly exergonic, proceeding with a free energy change of 142 kcal/mol at room temperature. Kinetic barriers however prevent the reaction from proceeding smoothly. The breakthrough came in 1948, when Reppe and Schweckendiek reported their wartime results showing that nickel compounds are effective catalysts: : 3 RC2H -> C6R3H3 Since this discovery, many other cyclotrimerisations have been reported. Mechanism In terms of mechanism, the reactions beg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IR Spectrum
Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functional groups in solid, liquid, or gaseous forms. It can be used to characterize new materials or identify and verify known and unknown samples. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) which produces an infrared spectrum. An IR spectrum can be visualized in a graph of infrared light absorbance (or transmittance) on the vertical axis vs. frequency, wavenumber or wavelength on the horizontal axis. Typical units of wavenumber used in IR spectra are reciprocal centimeters, with the symbol cm−1. Units of IR wavelength are commonly given in micrometers (formerly called "microns"), symbol μm, which are related to the wavenumber in a reciprocal way. A co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonylation
Carbonylation refers to reactions that introduce carbon monoxide into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry. The term carbonylation also refers to oxidation of protein side chains. Organic chemistry Several industrially useful organic chemicals are prepared by carbonylations, which can be highly selective reactions. Carbonylations produce organic carbonyls, i.e., compounds that contain the C=O functional group such as aldehydes, carboxylic acids and esters. Carbonylations are the basis of many types of reactions, including hydroformylation and Reppe reactions. These reactions require metal catalysts, which bind and activate the CO. These processes involve transition metal acyl complexes as intermediates. Much of this theme was developed by Walter Reppe. Hydroformylation Hydroformylation entails the addition of both carbon monoxide and hydrogen to unsaturated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandwich Complex
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 of X- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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