Organometallic homogeneous catalysts

Therefore It seems to be interesting to study such effects in the selective hydrogenation of a poly-unsaturated molecule as carvone. It was reported that the partial hydrogenation of this molecule is very sensitive to different homogeneous catalysts organometallic compounds (refs. 8-10), Zn/OH (ref. 11), NaBH (ref.12), and Zn-NiCl (ref. 13) as examples. 

C. Coperet, and J.-M. Basset, Strategies to Immobilize Well-Defined Olefin Metathesis Catalysts Supported Homogeneous Catalysis vs. Surface Organometallic Chemistry, Adv. Synth. Catal. 349, 78-92 (2007). 

Chiral bisoxazoline associated with palladium is a very efficient organometallic catalyst for the asymmetric allylic alkylation of allylic acetates and carbonates, allowing the formation of carbon-carbon as well as carbon-heteroatom bond in enantiomeric excesses higher than 95%.[1,2] However one of the problems in organometallic homogeneous catalysis is the separation of the catalyst, often toxic and very expensive, from the product(s) of the reaction. Very recently, a chiral fluorous bisoxazoline (Figure 3.1) has been shown to be an efficient ligand in the... 

There are a number of others in common industrial use, such as those used for polymerization of alkenes. One example of an organometallic homogeneous catalyst is the Zr(IV) complex [Zr(CH3)(T 5-Cp)2X], which operates by binding alkene monomers to the metal prior to addition to a growing carbon chain. A similar coordination of substrate is involved in the use of [Co(CO)4H] as catalyst in the hydroformylation of alkenes to aldehydes. Likewise, the [Rh(CO)2l2] ion, formed in situ, catalyses the carbonylation of methanol to acetic acid. 

Metal hydrides play a central role in modem inorganic and organometallic chemistry and find a wide applicability in several key sectors of the chemical industry as highly selective and efficient catalysts for homogeneous processes and new materials for energy storage. Their involvement in metalloenzymes attending at important biochemical processes has also been established and represents an active area of research. 

The liquid clathrate phase will dissolve substances that act as olefin hydrogenation catalysts, creating homogeneous hydrogenation catalysts.Polymerization catalysts comprised of stable liquid clathrate aluminoxane, aromatic solvents, and organic, inorganic, or organometallic compounds were described.Liquid clathrate compositions comprised of a metal halide, a quaternary ammonium salt, a quaternary phosphonium salt, or a ternary sulfonium salt an aluminum trihalide and an aromatic hydrocarbon have proven useful as reusable aluminum catalysts in Friedel-Crafts reactions. 

Blum Y, Czarkie D, Rahamim Y, Shvo Y (1985) (Cyclopentadienone)ruthenium carbonyl-complexes - a new class of homogeneous hydrogenation catalysts. Organometallics 4 1459-1461... 

Geoffrey Wilkinson (Imperial College, London) shared the 1973 Nobel Prize in Chemistry with Ernst 0. Fischer (Munich) for their achievements in organometallic chemistry. In addition to his work on catalysts for homogeneous hydrogenation, Wilkinson collaborated on determining the structure of ferrocene as well as numerous other aspects of organometallic compounds. 

Abstract The use of A-heterocyclic carbene (NHC) complexes as homogeneous catalysts in addition reactions across carbon-carbon double and triple bonds and carbon-heteroatom double bonds is described. The discussion is focused on the description of the catalytic systems, their current mechanistic understanding and occasionally the relevant organometallic chemistry. The reaction types covered include hydrogenation, transfer hydrogenation, hydrosilylation, hydroboration and diboration, hydroamination, hydrothiolation, hydration, hydroarylation, allylic substitution, addition, chloroesterification and chloroacylation. 

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