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Cobaltocene Crystals
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] |
American Elements
American Elements is a global manufacturer and distributor of advanced materials with a more than 35,000-page online product catalog and compendium of information on the chemical elements, advanced materials, and high technology applications. The company's headquarters and educational programs are based in Los Angeles, California. Its research and production facilities are located in Salt Lake City, Utah; Monterrey, Mexico; Baotou, China; and Manchester, UK. History American Elements began as a toll chemical manufacturer and refiner serving U.S. mining companies by producing metal-based chemicals from their deposits. In 1998, its two largest customers, the Unocal/Molycorp rare-earth mine in Mountain Pass, California and the Rhodia rare-earth refinery in Freeport, Texas closed, ending domestic U.S. rare-earth production. In response, the company established mining joint ventures in Inner Mongolia, China and in 1999 became one of the first post-Cold War companies to export rare-eart ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhodocene
Rhodocene is a chemical compound with the formula . Each molecule contains an atom of rhodium bound between two planar aromatic systems of five carbon atoms known as cyclopentadienyl rings in a sandwich arrangement. It is an organometallic compound as it has ( haptic) covalent rhodium–carbon bonds. The radical is found above or when trapped by cooling to liquid nitrogen temperatures (). At room temperature, pairs of these radicals join via their cyclopentadienyl rings to form a dimer, a yellow solid. The history of organometallic chemistry includes the 19th-century discoveries of Zeise's salt and nickel tetracarbonyl. These compounds posed a challenge to chemists as the compounds did not fit with existing chemical bonding models. A further challenge arose with the discovery of ferrocene, the iron analogue of rhodocene and the first of the class of compounds now known as metallocenes. Ferrocene was found to be unusually chemically stable, as were analogous chemical struct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metallocenes
A metallocene is a compound typically consisting of two cyclopentadienyl anions (, abbreviated Cp) bound to a metal center (M) in the oxidation state II, with the resulting general formula Closely related to the metallocenes are the metallocene derivatives, e.g. titanocene dichloride, vanadocene dichloride. Certain metallocenes and their derivatives exhibit catalytic properties, although metallocenes are rarely used industrially. Cationic group 4 metallocene derivatives related to p2ZrCH3sup>+ catalyze olefin polymerization. Some metallocenes consist of metal plus two cyclooctatetraenide anions (, abbreviated cot2−), namely the lanthanocenes and the actinocenes (uranocene and others). Metallocenes are a subset of a broader class of compounds called sandwich compounds. In the structure shown at right, the two pentagons are the cyclopentadienyl anions with circles inside them indicating they are aromatically stabilized. Here they are shown in a staggered conformation. Hist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organocobalt Compounds
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] |
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] |
Carbon Monoxide
Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simplest molecule of the oxocarbon family. In coordination complexes the carbon monoxide ligand is called carbonyl. It is a key ingredient in many processes in industrial chemistry. The most common source of carbon monoxide is the partial combustion of carbon-containing compounds, when insufficient oxygen or heat is present to produce carbon dioxide. There are also numerous environmental and biological sources that generate and emit a significant amount of carbon monoxide. It is important in the production of many compounds, including drugs, fragrances, and fuels. Upon emission into the atmosphere, carbon monoxide affects several processes that contribute to climate change. Carbon monoxide has important biological roles across phylogenetic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Half-reaction
A half reaction (or half-cell reaction) is either the oxidation or reduction reaction component of a redox reaction. A half reaction is obtained by considering the change in oxidation states of individual substances involved in the redox reaction. Often, the concept of half reactions is used to describe what occurs in an electrochemical cell, such as a Galvanic cell battery. Half reactions can be written to describe both the metal undergoing oxidation (known as the anode) and the metal undergoing reduction (known as the cathode). Half reactions are often used as a method of balancing redox reactions. For oxidation-reduction reactions in acidic conditions, after balancing the atoms and oxidation numbers, one will need to add H+ ions to balance the hydrogen ions in the half reaction. For oxidation-reduction reactions in basic conditions, after balancing the atoms and oxidation numbers, first treat it as an acidic solution and then add OH− ions to balance the H+ ions in the half rea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferrocenium
Ferrocenium tetrafluoroborate is an organometallic compound with the formula e(C5H5)2F4. This salt is composed of the cation e(C5H5)2sup>+ and the tetrafluoroborate anion (). The related hexafluorophosphate is also a popular reagent with similar properties. The cation is often abbreviated Fc+ or Cp2Fe+. The salt is deep blue in color and paramagnetic. Ferrocenium salts are sometimes used as one-electron oxidizing agents, and the reduced product, ferrocene, is inert and readily separated from ionic products. The ferrocene–ferrocenium couple is often used as a reference in electrochemistry. The standard potential of ferrocene-ferrocenium is 0.400 V vs. the normal hydrogen electrode (NHE) and is often assumed to be invariant between different solvents. Preparation Commercially available, this compound may be prepared by oxidizing ferrocene typically with ferric salts followed by addition of fluoroboric acid. A variety of other oxidants work well also, such as nitrosyl tetr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reduction Potential
Redox potential (also known as oxidation / reduction potential, ''ORP'', ''pe'', ''E_'', or E_) is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respectively. Redox potential is expressed in volts (V). Each species has its own intrinsic redox potential; for example, the more positive the reduction potential (reduction potential is more often used due to general formalism in electrochemistry), the greater the species' affinity for electrons and tendency to be reduced. Measurement and interpretation In aqueous solutions, redox potential is a measure of the tendency of the solution to either gain or lose electrons when it is subjected to change by introduction of a new species. A solution with a higher (more positive) reduction potential than the new species will have a tendency to gain electrons from the new species (i.e. to be reduced by oxidizing the new species) and a solution with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decamethylcobaltocene
Decamethylcobaltocene is an organocobalt compound with the formula Co(C5(CH3)5)2, abbreviated CoCp{{su, p=∗, b=2. It is a dark brown solid. This compound is used as a strong reducing agent in organometallic chemistry. Synthesis Decamethylcobaltocene is prepared by treatment of LiCp* with CoCl2: :2 LiCp* + CoCl2 → 2 LiCl + CoCp*2 The permethylated form is more air-sensitive than the parent cobaltocene, owing to the inductive effects of methyl groups. It is a thermally stable compound and undergoes vacuum sublimation. Bonding Co(C5Me5)2 is a metallocene, having idealized D5d symmetry. Like cobaltocene, decamethylcobaltocene has a 19 electron count in its valence shell and is paramagnetic. It is used as a one-electron reducing agent. Relative to the ferrocene/ferrocenium couple, the redox potential for the oCp*2sup>+/0 couple is -1.94 V compared to the oCp2sup>+/0 couple of -1.33 V (in dichloromethane). For comparison, the difference between the redox ferrocen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Internal Standard
An internal standard in analytical chemistry is a chemical substance that is added in a constant amount to samples, the blank and calibration standards in a chemical analysis. This substance can then be used for calibration by plotting the ratio of the analyte signal to the internal standard signal as a function of the analyte concentration of the standards. This is done to correct for the loss of analyte during sample preparation or sample inlet. The internal standard is a compound that is very similar, but not identical to the chemical species of interest in the samples, as the effects of sample preparation should, relative to the amount of each species, be the same for the signal from the internal standard as for the signal(s) from the species of interest in the ideal case. Adding known quantities of analyte(s) of interest is a distinct technique called standard addition, which is performed to correct for matrix effects. This ratio for the samples is then used to obtain their anal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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