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Chlorobis(cyclooctene)rhodium Dimer
Chlorobis(cyclooctene)rhodium dimer is an organorhodium compound with the formula Rh2Cl2(C8H14)4, where C8H14 is ''cis''-cyclooctene. Sometimes abbreviated Rh2Cl2(coe)4, it is a red-brown, air-sensitive solid that is a precursor to many other organorhodium compounds and catalysts. The complex is prepared by treating an alcohol solution of hydrated rhodium trichloride with cyclooctene at room temperature. The coe ligands are easily displaced by other more basic ligands, more so than the diene ligands in the related complex cyclooctadiene rhodium chloride dimer. Catalyst for C-H activation C-H activation is often catalyzed by chlorobis(cyclooctene)rhodium dimer as demonstrated in the synthesis of a strained bicyclic enamine. : The synthesis of a mescaline analogue involves enantioselective annulation of an aryl imine via a C-H activation. The total synthesis of lithospermic acid employs "guided C-H functionalization" late stage to a highly functionalized system. The directing gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organorhodium Compound
Organorhodium chemistry is the chemistry of organometallic compounds containing a rhodium-carbon chemical bond, and the study of rhodium and rhodium compounds as catalysts in organic reactions. Stable organorhodium compounds and transient organorhodium intermediates are used as catalyst such as in olefin hydroformylation, olefin hydrogenation, olefin isomerization and the Monsanto process Classification based on principal oxidation states Organometallic rhodium compounds share many characteristics with those of iridium, but less so with cobalt. Rhodium can exist in oxidation states of -III to +V, but rhodium(I) and rhodium(III) are the more common. Rhodium(I) compounds (d8 configuration) usually occur with square planar or trigonal bipyramidal geometries, while rhodium (III) compounds (d6 configuration) typically have an octahedral geometry. Rhodium(0) Rhodium(0) complexes are binary carbonyls, the principal examples being tetrarhodium dodecacarbonyl, Rh4(CO)12, and hexadecacarb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclooctene
Cyclooctene is the cycloalkene with a formula . Its molecule has a ring of 8 carbon atoms, connected by seven single bonds and one double bond. Cyclooctene is notable because it is the smallest cycloalkene that can exist stably as either the ''cis'' or ''trans'' stereoisomer, with ''cis''-cyclooctene being the most common. Theoretical analysis implies a total of 16 conformational and configurational isomers, all chiral, forming 8 enantiomeric In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical ant ... pairs. The ''cis'' isomer can adopt various conformations, the most stable one being shaped like a ribbon. The most stable conformation of ''trans''-cyclooctene is shaped like the 8-carbon equivalent of the chair conformation of cyclohexane. Longer cycloalkene rings such as the ten-c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Of Crystallization
In chemistry, water(s) of crystallization or water(s) of hydration are water molecules that are present inside crystals. Water is often incorporated in the formation of crystals from aqueous solutions. In some contexts, water of crystallization is the total mass of water in a substance at a given temperature and is mostly present in a definite (stoichiometric) ratio. Classically, "water of crystallization" refers to water that is found in the crystalline framework of a metal complex or a salt, which is not directly bonded to the metal cation. Upon crystallization from water, or water-containing solvents, many compounds incorporate water molecules in their crystalline frameworks. Water of crystallization can generally be removed by heating a sample but the crystalline properties are often lost. Compared to inorganic salts, proteins crystallize with large amounts of water in the crystal lattice. A water content of 50% is not uncommon for proteins. Applications Knowledge of hyd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhodium Trichloride
Rhodium(III) chloride refers to inorganic compounds with the formula RhCl3(H2O)''n'', where ''n'' varies from 0 to 3. These are diamagnetic solids featuring octahedral Rh(III) centres. Depending on the value of ''n'', the material is either a dense brown solid or a soluble reddish salt. The soluble trihydrated (n = 3) salt is widely used to prepare compounds used in homogeneous catalysis, notably for the industrial production of acetic acid and hydroformylation. Structures Aqueous solutions of RhCl3(H2O)3 have been characterized by 103Rh NMR spectroscopy, which shows the presence of several species. The proportions of which change with time and depend on the concentration of chloride. The relative distribution of these species determines the colour of the solutions, which can range from yellow (the hexaaquo ion) to "raspberry-red". Some of these species are h(H2O)6sup>3+, hCl(H2O)5sup>2+, ''cis''- and ''trans''- hCl2(H2O)4sup>+, and hCl3(H2O)3 Individual ions have been sep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ligand
In coordination chemistry, a ligand is an ion or molecule (functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands". Metals and metalloids are bound to ligands in almost all circumstances, although gaseous "naked" metal ions can be generated in a high vacuum. Ligands in a complex dictate the reactivity of the central atom, including ligand substitution rates, the reactivity of the ligands themselves, and redox. Ligand selection requires critical consideration in many practical areas, including bioinorganic and medicinal chemistry, homogeneous catalysis, and environmental chemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclooctadiene Rhodium Chloride Dimer
Cyclooctadiene rhodium chloride dimer is the organorhodium compound with the formula Rh2Cl2(C8H12)2, commonly abbreviated [RhCl(COD)]2 or Rh2Cl2(COD)2. This yellow-orange, air-stable compound is a widely used precursor to homogeneous catalysis, homogeneous catalysts.Giordano, G.; Crabtree, R. H. “Di-μ-chloro-bis(η4-1,5-cyclooctadiene)dirhodium(I)” Inorganic Syntheses, 1990, volume 28, pages 88-90. Preparation and reactions The synthesis of [RhCl(COD)]2 involves heating a solution of hydrated rhodium trichloride with 1,5-cyclooctadiene in aqueous ethanol in the presence of sodium carbonate: :2 RhCl3·3H2O + 2 COD + 2 CH3CH2OH + 2 Na2CO3 → [RhCl(COD)]2 + 2 acetaldehyde, CH3CHO + 8 H2O + 2 CO2 + 4 NaCl [RhCl(COD)]2 is principally used as a source of the electrophile "[Rh(COD)]+." :[RhCl(COD)]2 + L → [LRh(COD)]+Cl− (where L = PR3, alkene, etc. and = 2 or 3) In this way, Chirality (chemistry), chiral phosphines can be attached to Rh. The resulting chiral complexes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chirality (chemistry)
In chemistry, a molecule or ion is called chiral () if it cannot be superposed on its mirror image by any combination of rotation (geometry), rotations, translation (geometry), translations, and some Conformational isomerism, conformational changes. This geometric property is called chirality (). The terms are derived from Ancient Greek χείρ (''cheir'') 'hand'; which is the canonical example of an object with this property. A chiral molecule or ion exists in two stereoisomers that are mirror images of each other, called enantiomers; they are often distinguished as either "right-handed" or "left-handed" by their absolute configuration or some other criterion. The two enantiomers have the same chemical properties, except when reacting with other chiral compounds. They also have the same physics, physical properties, except that they often have opposite optical activity, optical activities. A homogeneous mixture of the two enantiomers in equal parts is said to be racemic mixtu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Product Synth Ellman Figure 1
Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are part of nature, human activity is often understood as a separate category from other natural phenomena. The word ''nature'' is borrowed from the Old French ''nature'' and is derived from the Latin word ''natura'', or "essential qualities, innate disposition", and in ancient times, literally meant " birth". In ancient philosophy, ''natura'' is mostly used as the Latin translation of the Greek word '' physis'' (φύσις), which originally related to the intrinsic characteristics of plants, animals, and other features of the world to develop of their own accord. The concept of nature as a whole, the physical universe, is one of several expansions of the original notion; it began with certain core applications of the word φύσις by pre-So ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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