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Rhodium(II) Trifluoroacetate
Rhodium trifluoroacetate is the chemical compound with the formula . It is used as a catalyst in the synthesis of some organic compounds. The compound and its derivatives have been extensively characterized by X-ray crystallography. It adopts the Chinese lantern structure seen for many di metal carboxylate complexes. This structure accommodates a Rh-Rh bond, the existence of which explains the diamagnetism of this Rh(II) species. The Rh-Rh distance is 238 pm. The anhydrous complex is a green volatile solid. It is prepared by dissolving rhodium(II) acetate in hot trifluoroacetic acid: : This reaction expels acetic acid. The Rh-Rh bond is retained. Reactions Rhodium(II) trifluoroacetate forms adducts with a variety of Lewis bases. The structures typically have a 2:1 stoichiometry, with one base binding at the "axial" position on each of the two Rh(II) centers: : (L = CO, RCN, R2SO, R3P, ...) Rhodium(II) trifluoroacetate binds even very weak bases, moreso than does rhodi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Synthesis
Organic synthesis is a branch of chemical synthesis concerned with the construction of organic compounds. Organic compounds are molecules consisting of combinations of covalently-linked hydrogen, carbon, oxygen, and nitrogen atoms. Within the general subject of organic synthesis, there are many different types of synthetic routes that can be completed including total synthesis, Enantioselective synthesis, stereoselective synthesis, automated synthesis, and many more. Additionally, in understanding organic synthesis it is necessary to be familiar with the methodology, techniques, and applications of the subject. Total synthesis A total synthesis refers to the complete chemical synthesis of molecules from simple, Precursor (chemistry), natural precursors. Total synthesis is accomplished either via a linear or convergent approach. In a Linear synthesis, ''linear'' synthesis—often adequate for simple structures—several steps are performed sequentially until the molecule is com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Crystallography
X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring the angles and intensities of the X-ray diffraction, a crystallography, crystallographer can produce a three-dimensional picture of the density of electrons within the crystal and the positions of the atoms, as well as their chemical bonds, crystallographic disorder, and other information. X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences between various materials, especially minerals and alloys. The method has also revealed the structure and function of many biological molecules, including vitamins, drugs, proteins and nucleic acids such as DNA. X-ray crystall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinese Lantern Structure
In chemistry, the Chinese lantern structure is a coordination complex where two metal atoms are bridged by four Denticity, bidentate ligands. This structure type is also known as a paddlewheel complex. Examples include chromium(II) acetate, molybdenum(II) acetate, and rhodium(II) acetate, copper(II) acetate dihydrate. The name is derived from the resemblance between the structure and a Chinese paper lantern. Often additional ligands are bound to the metal centers along the M---M vector. The degree of metal-metal bonding varies according to the d-electron configuration. Complexes with Chinese lantern structure *Copper benzoate *Copper acetate *Chromium(II) acetate *Molybdenum(II) acetate *Diruthenium tetraacetate chloride *Rhodium acetate References Further reading * Coordination chemistry {{inorganic-chem-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Carboxylate Complex
Transition metal carboxylate complexes are coordination complexes with carboxylate (RCO2−) ligands. Reflecting the diversity of carboxylic acids, the inventory of metal carboxylates is large. Many are useful commercially, and many have attracted intense scholarly scrutiny. Carboxylates exhibit a variety of coordination modes, most common are κ1- (O-monodentate), κ2 (O,O-bidentate), and bridging. Acetate and related monocarboxylates Structure and bonding Carboxylates bind to single metals by one or both oxygen atoms, the respective notation being κ1- and κ2-. In terms of electron counting, κ1-carboxylates are "X"-type ligands, i.e., a pseudohalide-like. κ2-carboxylates are "L-X ligands", i.e. resembling the combination of a Lewis base (L) and a pseudohalide (X). Carboxylates are classified as hard ligands, in HSAB theory. File:BasicFeacetate.png, Basic ferric acetate File:Ag2(OAc)2.png, Silver acetate File:BasicZnAcetate.png, Basic zinc acetate File:Mo2(OAc)4.svg, M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Picometer
The picometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: pm) or picometer ( American spelling) is a unit of length in the International System of Units (SI), equal to , or one trillionth of a metre, which is the SI base unit of length. The picometre is one thousand femtometres, one thousandth of a nanometre ( nm), one millionth of a micrometre (also known as a micron), one billionth of a millimetre, and one trillionth of a metre. The symbol μμ was once used for it. It is also one hundredth of an ångström, an internationally known (but non-SI) unit of length. Use The picometre's length is of an order so small that its application is almost entirely confined to particle physics, quantum physics, chemistry, and acoustics. Atoms are between 62 and 520 pm in diameter, and the typical length of a carbon–carbon single bond is 154 pm. Smaller units still may be used to describe smaller particles (some of which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhodium(II) Acetate
Rhodium(II) acetate is the coordination compound with the formula Rh2(AcO)4, where AcO− is the acetate ion (). This dark green powder is slightly soluble in polar solvents, including water. It is used as a catalyst for cyclopropanation of alkenes. It is a widely studied example of a transition metal carboxylate complex. Preparation Rhodium(II) acetate is usually prepared by the heating of hydrated rhodium(III) chloride in a methanol-acetic acid mixture. The crude product is the bis(methanol) complex, but it is easily desolvated. Structure and properties The structure of rhodium(II) acetate features a pair of rhodium atoms, each with octahedral molecular geometry, defined by four acetate oxygen atoms, water, and a Rh–Rh bond of length 2.39 Å. The water adduct is exchangeable, and a variety of other Lewis bases bind to the axial positions. Copper(II) acetate and chromium(II) acetate adopt similar structures. Chemical properties The dimer binds a number of classical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stoichiometry
Stoichiometry () is the relationships between the masses of reactants and Product (chemistry), products before, during, and following chemical reactions. Stoichiometry is based on the law of conservation of mass; the total mass of reactants must equal the total mass of products, so the relationship between reactants and products must form a ratio of positive integers. This means that if the amounts of the separate reactants are known, then the amount of the product can be calculated. Conversely, if one reactant has a known quantity and the quantity of the products can be empirically determined, then the amount of the other reactants can also be calculated. This is illustrated in the image here, where the unbalanced equation is: : : However, the current equation is imbalanced. The reactants have 4 hydrogen and 2 oxygen atoms, while the product has 2 hydrogen and 3 oxygen. To balance the hydrogen, a coefficient of 2 is added to the product H2O, and to fix the imbalance of oxygen, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexamethylbenzene
Hexamethylbenzene, also known as mellitene, is a hydrocarbon with the molecular formula C12H18 and the condensed structural formula C6(CH3)6. It is an aromatic compound and a derivative of benzene, where benzene's six hydrogen atoms have each been replaced by a methyl group. In 1929, Kathleen Lonsdale reported the crystal structure of hexamethylbenzene, demonstrating that the central ring is hexagonal and flat and thereby ending an ongoing debate about the physical parameters of the benzene system. This was a historically significant result, both for the field of X-ray crystallography and for understanding aromaticity. Hexamethylbenzene can be oxidised to mellitic acid, which is found in nature as its aluminium salt in the rare mineral mellite. Hexamethylbenzene can be used as a ligand in organometallic compounds. An example from organoruthenium chemistry shows structural change in the ligand associated with changes in the oxidation state of the metal centre, though the same ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclopropanation
In organic chemistry, cyclopropanation refers to any chemical process which generates cyclopropane () Ring (chemistry), rings. It is an important process in modern chemistry as many useful compounds bear this motif; for example pyrethroid insecticides and a number of quinolone antibiotics (ciprofloxacin, sparfloxacin, etc.). However, the high ring strain present in cyclopropanes makes them challenging to produce and generally requires the use of highly Reactivity (chemistry), reactive species, such as carbenes, ylids and carbanions. Many of the reactions proceed in a cheletropic reaction, cheletropic manner. Approaches From alkenes using carbenoid reagents Several methods exist for converting alkenes to cyclopropane rings using carbene type reagents. As carbenes themselves are highly reactive it is common for them to be used in a stabilised form, referred to as a carbenoid. Simmons–Smith reaction In the Simmons–Smith reaction the reactive carbenoid is iodomethylzinc iodide, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhodium(II) Compounds
Rhodium is a chemical element; it has symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isotope, which is 103Rh. Naturally occurring rhodium is usually found as a free metal or as an alloy with similar metals and rarely as a chemical compound in minerals such as bowieite and rhodplumsite. It is one of the rarest and most valuable precious metals. Rhodium is a group 9 element (cobalt group). Rhodium is found in platinum or nickel ores with the other members of the platinum group metals. It was discovered in 1803 by William Hyde Wollaston in one such ore, and named for the rose color of one of its chlorine compounds. The element's major use (consuming about 80% of world rhodium production) is as one of the catalysts in the three-way catalytic converters in automobiles. Because rhodium metal is inert against corrosion and most agg ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
