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Tetrakis(1-norbornyl)cobalt(IV)
Tetrakis(1-norbornyl)cobalt(IV) is an air-sensitive organometallic compound of cobalt. It was first synthesized by Barton K. Bower and Howard G. Tennent in 1972 and is one of few compounds in which cobalt has a formal oxidations state of +4. Preparation Tetrakis(1-norbornyl)cobalt(IV) is formed the reaction of CoCl2•THF with 1-norbornyllithium (norLi) in ''n''-pentane under an inert atmosphere. The cobalt(II) chloride-THF adduct is prepared from Soxhlet extraction of anhydrous CoCl2 with THF, and the organolithium reagent is prepared from the reaction between 1-chloro-norbornane and lithium metal. : + 4 norLi ->text] + + 4 + 2 THF : The compound can then be purified by Recrystallization (chemistry), recrystallization. Properties The complex is a thermally stable homoleptic tetraorganylcobalt(IV) complex with exclusively ''σ''-bonding ligands. It was the first low-spin complex with tetrahedral geometry to be isolated. Stability The exceptional stability of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrakis(1-norbornyl)cobalt(IV)
Tetrakis(1-norbornyl)cobalt(IV) is an air-sensitive organometallic compound of cobalt. It was first synthesized by Barton K. Bower and Howard G. Tennent in 1972 and is one of few compounds in which cobalt has a formal oxidations state of +4. Preparation Tetrakis(1-norbornyl)cobalt(IV) is formed the reaction of CoCl2•THF with 1-norbornyllithium (norLi) in ''n''-pentane under an inert atmosphere. The cobalt(II) chloride-THF adduct is prepared from Soxhlet extraction of anhydrous CoCl2 with THF, and the organolithium reagent is prepared from the reaction between 1-chloro-norbornane and lithium metal. : + 4 norLi ->text] + + 4 + 2 THF : The compound can then be purified by Recrystallization (chemistry), recrystallization. Properties The complex is a thermally stable homoleptic tetraorganylcobalt(IV) complex with exclusively ''σ''-bonding ligands. It was the first low-spin complex with tetrahedral geometry to be isolated. Stability The exceptional stability of t ... [...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] |
Cobalt(II) Chloride
Cobalt(II) chloride is an inorganic compound of cobalt and chlorine, with the formula . The compound forms several hydrates ·''n'', for ''n'' = 1, 2, 6, and 9. Claims of the formation of tri- and tetrahydrates have not been confirmed.M. T. Saugier, M. Noailly, R. Cohen-Adad, F. Paulik, and J. Paulik (1977): "Equilibres solide ⇄ liquide ⇆ vapeur du systeme binaire -" ''Journal of Thermal Analysis'', volume 11, issue 1, pages 87–100. Note: the lowest point of fig.6 is inconsistent with fig.7; probably should be at -27.8 C instead of 0 C. The anhydrous form is a blue crystalline solid; the dihydrate is purple and the hexahydrate is pink. Commercial samples are usually the hexahydrate, which is one of the most commonly used cobalt compounds in the lab. Properties Anhydrous At room temperature, anhydrous cobalt chloride has the cadmium chloride structure () (Rm) in which the cobalt(II) ions are octahedrally coordinated. At about 706 °C (20 degrees below the melting poi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrahedral Geometry
In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron. The bond angles are cos−1(−) = 109.4712206...° ≈ 109.5° when all four substituents are the same, as in methane () as well as its heavier analogues. Methane and other perfectly symmetrical tetrahedral molecules belong to point group Td, but most tetrahedral molecules have lower symmetry. Tetrahedral molecules can be chiral. Tetrahedral bond angle The bond angle for a symmetric tetrahedral molecule such as CH4 may be calculated using the dot product of two vectors. As shown in the diagram, the molecule can be inscribed in a cube with the tetravalent atom (e.g. carbon) at the cube centre which is the origin of coordinates, O. The four monovalent atoms (e.g. hydrogens) are at four corners of the cube (A, B, C, D) chosen so that no two atoms are at adjacent corners linked by only one cube edge. If the edge length of the cube ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-coordinating Anion
Anions that interact weakly with cations are termed non-coordinating anions, although a more accurate term is weakly coordinating anion. Non-coordinating anions are useful in studying the reactivity of electrophilic cations. They are commonly found as counterions for cationic metal complexes with an unsaturated coordination sphere. These special anions are essential components of homogeneous alkene polymerisation catalysts, where the active catalyst is a coordinatively unsaturated, cationic transition metal complex. For example, they are employed as counterions for the 14 valence electron cations C5H5)2ZrRsup>+ (R = methyl or a growing polyethylene chain). Complexes derived from non-coordinating anions have been used to catalyze hydrogenation, hydrosilylation, oligomerization, and the living polymerization of alkenes. The popularization of non-coordinating anions has contributed to increased understanding of agostic complexes wherein hydrocarbons and hydrogen serve as ligands. N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silver Tetrafluoroborate
Silver tetrafluoroborate is an inorganic compound with the chemical formula AgBF4. It is a white solid that dissolves in polar organic solvents as well as water. In its solid state, the Ag+ centers are bound to fluoride. Preparation Silver tetrafluoroborate is prepared by the reaction between boron trifluoride and silver oxide in the presence of benzene. Laboratory uses In the inorganic and organometallic chemistry laboratory, silver tetrafluoroborate, sometimes referred to "silver BF-4", is a useful reagent. In dichloromethane, silver tetrafluoroborate is a moderately strong oxidant. Similar to silver hexafluorophosphate, it is commonly used to replace halide anions or ligands with the weakly coordinating tetrafluoroborate anions. The abstraction of the halide is driven by the precipitation of the appropriate silver halide A silver halide (or silver salt) is one of the chemical compounds that can form between the element silver (Ag) and one of the halogens. In particular, br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paramagnetic
Paramagnetism is a form of magnetism whereby some materials are weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. In contrast with this behavior, diamagnetic materials are repelled by magnetic fields and form induced magnetic fields in the direction opposite to that of the applied magnetic field. Paramagnetic materials include most chemical elements and some compounds; they have a relative magnetic permeability slightly greater than 1 (i.e., a small positive magnetic susceptibility) and hence are attracted to magnetic fields. The magnetic moment induced by the applied field is linear in the field strength and rather weak. It typically requires a sensitive analytical balance to detect the effect and modern measurements on paramagnetic materials are often conducted with a SQUID magnetometer. Paramagnetism is due to the presence of unpaired electrons in the material, so most atoms wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Counterion
160px, Polystyrene sulfonate, a cation-exchange resin, is typically supplied with as the counterion.">cation-exchange_resin.html" ;"title="Polystyrene sulfonate, a cation-exchange resin">Polystyrene sulfonate, a cation-exchange resin, is typically supplied with as the counterion. In chemistry, a counterion (sometimes written as "counter ion", pronounced as such) is the ion that accompanies an Ionic compound, ionic species in order to maintain Electric charge, electric neutrality. In table salt (NaCl, also known as sodium chloride) the sodium ion (positively charged) is the counterion for the chloride ion (negatively charged) and vice versa. A counterion will be more commonly referred to as an anion or a cation, depending on whether it is negatively or positively charged. Thus, the counterion to an anion will be a cation, and vice versa. In biochemistry, counterions are generally vaguely defined. Depending on their charge, proteins are associated with a variety of smaller ani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solvation
Solvation (or dissolution) describes the interaction of a solvent with dissolved molecules. Both ionized and uncharged molecules interact strongly with a solvent, and the strength and nature of this interaction influence many properties of the solute, including solubility, reactivity, and color, as well as influencing the properties of the solvent such as its viscosity and density. If the attractive forces between the solvent and solute particles are greater than the attractive forces holding the solute particles together, the solvent particles pull the solute particles apart and surround them. The surrounded solute particles then move away from the solid solute and out into the solution. Ions are surrounded by a concentric shell of solvent. Solvation is the process of reorganizing solvent and solute molecules into solvation complexes and involves bond formation, hydrogen bonding, and van der Waals forces. Solvation of a solute by water is called hydration. Solubility of solid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diethyl Ether
Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable liquid. It is commonly used as a solvent in laboratories and as a starting fluid for some engines. It was formerly used as a general anesthetic, until non-flammable drugs were developed, such as halothane. It has been used as a recreational drug to cause intoxication. Production Most diethyl ether is produced as a byproduct of the vapor-phase hydration of ethylene to make ethanol. This process uses solid-supported phosphoric acid catalysts and can be adjusted to make more ether if the need arises. Vapor-phase dehydration of ethanol over some alumina catalysts can give diethyl ether yields of up to 95%. Diethyl ether can be prepared both in laboratories and on an industrial scale by the acid ether synthesis. Ethanol is mixed with a stro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paramagnetism
Paramagnetism is a form of magnetism whereby some materials are weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. In contrast with this behavior, diamagnetic materials are repelled by magnetic fields and form induced magnetic fields in the direction opposite to that of the applied magnetic field. Paramagnetic materials include most chemical elements and some compounds; they have a relative magnetic permeability slightly greater than 1 (i.e., a small positive magnetic susceptibility) and hence are attracted to magnetic fields. The magnetic moment induced by the applied field is linear in the field strength and rather weak. It typically requires a sensitive analytical balance to detect the effect and modern measurements on paramagnetic materials are often conducted with a SQUID magnetometer. Paramagnetism is due to the presence of unpaired electrons in the material, so most atoms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetochemistry
Magnetochemistry is concerned with the magnetic properties of chemical compounds. Magnetic properties arise from the spin and orbital angular momentum of the electrons contained in a compound. Compounds are diamagnetic when they contain no unpaired electrons. Molecular compounds that contain one or more unpaired electrons are paramagnetic. The magnitude of the paramagnetism is expressed as an effective magnetic moment, μeff. For first-row transition metals the magnitude of μeff is, to a first approximation, a simple function of the number of unpaired electrons, the spin-only formula. In general, spin-orbit coupling causes μeff to deviate from the spin-only formula. For the heavier transition metals, lanthanides and actinides, spin-orbit coupling cannot be ignored. Exchange interaction can occur in clusters and infinite lattices, resulting in ferromagnetism, antiferromagnetism or ferrimagnetism depending on the relative orientations of the individual spins. Magnetic susceptibil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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