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Transition Metal Complexes Of Aldehydes And Ketones
Transition metal complexes of aldehydes and ketones describes coordination complexes with aldehyde (RCHO) and ketone ligands. Because aldehydes and ketones are common, the area is of fundamental interest. Some reactions that are useful in organic chemistry involve such complexes. Structure and bonding In monometallic complexes, aldehydes and ketones can bind to metals in either of two modes, η1-O-bonded and η2-C,O-bonded. These bonding modes are sometimes referred to sigma- and pi-bonded. These forms may sometimes interconvert. The sigma bonding mode is more common for higher valence, Lewis-acidic metal centers (e.g., Zn2+). The pi-bonded mode is observed for low valence, electron-rich metal centers (e.g., Fe(0) and Os(0)). For the purpose of electron-counting, O-bonded ligands count as 2-electron "L ligands": they are Lewis bases. η2-C,O ligands are described as analogues of alkene ligands, i.e. the Dewar-Chatt-Duncanson model. η2-C,O ketones and aldehydes can funct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OsP2(CO)2(CH2O)
Osp (; it, Ospo) is a village in the City Municipality of Koper in the Littoral region of Slovenia. Overview The Osp Valley is a passage through the karst and coastal region of Istria. It extends from below the village of Črni Kal to the sea. The valley was shaped by the Osp River. Osp is also one of the oldest villages in Slovenia, first mentioned in 1067. It was the first villages on the Istrian peninsula to have a Slovene school. The village is well known for its rock walls, which offer free climbing all year long. The village is a border crossing into Italy, with the village of Crociata di Prebenico (Križpot), Caresana (Mačkolje), in the ''comune'' (municipality) of San Dorligo della Valle (Dolina). The parish church in the settlement is dedicated to Saint Peter Saint Peter; he, שמעון בר יונה, Šimʿōn bar Yōnāh; ar, سِمعَان بُطرُس, translit=Simʿa̅n Buṭrus; grc-gre, Πέτρος, Petros; cop, Ⲡⲉⲧⲣⲟⲥ, Petros; lat, Petrus; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enolate
In organic chemistry, enolates are organic anions derived from the deprotonation of carbonyl () compounds. Rarely isolated, they are widely used as reagents in the synthesis of organic compounds. Bonding and structure Enolate anions are electronically related to allyl anions. The anionic charge is delocalized over the oxygen and the two carbon sites. Thus they have the character of both an alkoxide and a carbanion. Although they are often drawn as being simple salts, in fact they adopt complicated structures often featuring aggregates. Preparation Deprotonation of enolizable ketones, aromatic alcohols, aldehydes, and esters gives enolates. With strong bases, the deprotonation is quantitative. Typically enolates are generated from using lithium diisopropylamide (LDA). Often, as in conventional Claisen condensations, Mannich reactions, and aldol condensations, enolates are generated in low concentrations with alkoxide bases. Under such conditions, they exist in low concent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organometallic Chemistry
Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and selenium, as well. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide (metal carbonyls), cyanide, or carbide, are generally considered to be organometallic as well. Some related compounds such as transition metal hydrides and metal phosphine complexes are often included in discussions of organometallic compounds, though strictly speaking, they are not necessarily organometallic. The related but distinct term " metalorganic compound" refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands. Metal β-diketonates, alkoxides, dialkylamides, and metal phosphine complexes are repres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lewis Acid Catalysis
In Lewis acid catalysis of organic reactions, a metal-based Lewis acid acts as an electron pair acceptor to increase the reactivity of a substrate. Common Lewis acid catalysts are based on main group metals such as aluminum, boron, silicon, and tin, as well as many early (titanium, zirconium) and late (iron, copper, zinc) d-block metals. The metal atom forms an adduct with a lone-pair bearing electronegative atom in the substrate, such as oxygen (both sp2 or sp3), nitrogen, sulfur, and halogens. The complexation has partial charge-transfer character and makes the lone-pair donor effectively more electronegative, activating the substrate toward nucleophilic attack, heterolytic bond cleavage, or cycloaddition with 1,3-dienes and 1,3-dipoles. Many classical reactions involving carbon–carbon or carbon–heteroatom bond formation can be catalyzed by Lewis acids. Examples include the Friedel-Crafts reaction, the aldol reaction, and various pericyclic processes that proceed slowly at r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diene
In organic chemistry a diene ( ) (diolefin ( ) or alkadiene) is a covalent compound that contains two double bonds, usually among carbon atoms. They thus contain two alk''ene'' units, with the standard prefix ''di'' of systematic nomenclature. As a subunit of more complex molecules, dienes occur in naturally occurring and synthetic chemicals and are used in organic synthesis. Conjugated dienes are widely used as monomers in the polymer industry. Polyunsaturated fats are of interest to nutrition. Classes Dienes can be divided into three classes, depending on the relative location of the double bonds: #Cumulated dienes have the double bonds sharing a common atom. The result is more specifically called an allene. #Conjugated dienes have conjugated double bonds separated by one single bond. Conjugated dienes are more stable than other dienes because of resonance. #Unconjugated dienes have the double bonds separated by two or more single bonds. They are usually less stable tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha-beta Unsaturated Carbonyl Compounds
Alphabeta is an Israeli musical group. Alphabeta or Alpha Beta may also refer to: *The Greek alphabet, from ''Alpha'' (Αα) and ''Beta'' (Ββ), the first two letters *Alpha Beta, a former chain of Californian supermarkets *Alpha and beta anomers (chemistry) *Alpha–beta pruning, a type of search algorithm *Alpha-beta transformation, a mathematical transformation in electrical engineering *Alpha-beta unsaturated carbonyl compounds, a class of organic compounds *Alpha beta filter, a predictive filter *Alpha (finance) and Beta (finance), two measures characterizing the return of an investment portfolio *The Alpha Betas, a fraternity in the ''Revenge of the Nerds ''Revenge of the Nerds'' is a 1984 American comedy film directed by Jeff Kanew and starring Robert Carradine, Anthony Edwards, Ted McGinley, and Bernie Casey. The film's plot chronicles a group of nerds at the fictional Adams College trying ...'' film series *''Alpha Betas,'' an animated webseries created by Chris B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metallacycle
In organometallic chemistry, a metallacycle is a derivative of a carbocyclic compound wherein a metal has replaced at least one carbon center; this is to some extent similar to heterocycles. Metallacycles appear frequently as reactive intermediates in catalysis, e.g. olefin metathesis and alkyne trimerization. In organic synthesis, directed ortho metalation is widely used for the functionalization of arene rings via C-H activation. One main effect that metallic atom substitution on a cyclic carbon compound is distorting the geometry due to the large size of typical metals. Nomenclature Typically, metallacycles are cyclic compounds with two metal carbon bonds. Many compounds containing metals in rings are known, for example chelate rings. Usually, such compounds are not classified as metallacycles, but the naming conventions are not rigidly followed. Within the area of coordination chemistry and supramolecular chemistry, examples include metallacrowns, metallacryptands, metalla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metal Acetylacetonates
Metal acetylacetonates are coordination complexes derived from the acetylacetonate anion () and metal ions, usually transition metals. The bidentate ligand acetylacetonate is often abbreviated acac. Typically both oxygen atoms bind to the metal to form a six-membered chelate ring. The simplest complexes have the formula M(acac)3 and M(acac)2. Mixed-ligand complexes, e.g. VO(acac)2, are also numerous. Variations of acetylacetonate have also been developed with myriad substituents in place of methyl (RCOCHCOR−). Many such complexes are soluble in organic solvents, in contrast to the related metal halides. Because of these properties, acac complexes are sometimes used as catalyst precursors and reagents. Applications include their use as NMR "shift reagents" and as catalysts for organic synthesis, and precursors to industrial hydroformylation catalysts. in some cases also binds to metals through the central carbon atom; this bonding mode is more common for the third-row transition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coordination Complex
A coordination complex consists of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''ligands'' or complexing agents. Many metal-containing compounds, especially those that include transition metals (elements like titanium that belong to the Periodic Table's d-block), are coordination complexes. Nomenclature and terminology Coordination complexes are so pervasive that their structures and reactions are described in many ways, sometimes confusingly. The atom within a ligand that is bonded to the central metal atom or ion is called the donor atom. In a typical complex, a metal ion is bonded to several donor atoms, which can be the same or different. A polydentate (multiple bonded) ligand is a molecule or ion that bonds to the central atom through several of the ligand's atoms; ligands with 2, 3, 4 or even 6 bonds to the central atom are common. These compl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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