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Ligand effective

When exclusively considering Lewis-add catalysis, the literature on ligand effects can be divided into studies describing quantitatively the effect of ligands on rates and equilibria of the individual steps in the catalytic cycle on one hand, and studies focused on the enantioselectivity of the reaction on the other. Interestingly, in the majority of the former investigations, aqueous media are employed. [Pg.75]

Studies of ligand effects on Lewis-acid catalysed reactions in water... [Pg.76]

Research on ligand effects in aqueous solution has mainly focused on two types of organic reactions ... [Pg.76]

There are a few documented examples of studies of ligand effects on hydrolysis reactions. Angelici et al." investigated the effect of a number of multidentate ligands on the copper(II) ion-catalysed hydrolysis of coordinated amino acid esters. The equilibrium constant for binding of the ester and the rate constant for the hydrolysis of the resulting complex both decrease in the presence of ligands. Similar conclusions have been reached by Hay and Morris, who studied the effect of ethylenediamine... [Pg.76]

In Chapter 2 the Diels-Alder reaction between substituted 3-phenyl-l-(2-pyridyl)-2-propene-l-ones (3.8a-g) and cyclopentadiene (3.9) was described. It was demonstrated that Lewis-acid catalysis of this reaction can lead to impressive accelerations, particularly in aqueous media. In this chapter the effects of ligands attached to the catalyst are described. Ligand effects on the kinetics of the Diels-Alder reaction can be separated into influences on the equilibrium constant for binding of the dienoplule to the catalyst (K ) as well as influences on the rate constant for reaction of the complex with cyclopentadiene (kc-ad (Scheme 3.5). Also the influence of ligands on the endo-exo selectivity are examined. Finally, and perhaps most interestingly, studies aimed at enantioselective catalysis are presented, resulting in the first example of enantioselective Lewis-acid catalysis of an organic transformation in water. [Pg.82]

The ligand effect seems to depend on the substrates. Treatment of the prostaglandin precursor 73 with Pd(Ph3P)4 produces only the 0-allylated product 74. The use of dppe effects a [1,3] rearrangement to produce the cyclopen ta-none 75(55]. Usually a five-membered ring, rather than seven-membered, is predominantly formed. The exceptionally exclusive formation of seven-membered ring compound 77 from 76 is explained by the inductive effect of an oxygen adjacent to the allyl system in the intermediate complex[56]. [Pg.302]

Similar additions may be performed with the enamine 13. However, with 3-buten-2-one or methyl 2-propenoate Lewis acid catalysis is needed to activate the Michael acceptor chloro-trimethylsilane proved to be best suited for this purpose. A remarkable solvent effect is seen in these reactions. A change from THF to HMPA/toluene (1 1) results in a reversal of the absolute configuration of the product 14, presumably due to a ligand effect of HMPA235. [Pg.985]

Empirical approach to ligand effects on the kinetics of substitution and redox reactions. V. Gut-mann and R. Schmid, Coord. Chem. Rev., 1974,12, 263-293 (90). [Pg.40]

Organocobalt B models axial ligand effects on the structure and coordination chemistry of coba-loximes. N. Bresciani-Pahor, M. Forcohin, L. G. Marzilli, L. Randaccio, M. F. Summers and P. J. Toscano, Coord. Chem. Rev., 1985, 63,1 (263). [Pg.67]

Effects related to the changes in the electronic structure of a-toms after alloying or formation of bimetallics(electronic or ligand ( ) effects). [Pg.267]

The state of the knowledge is at the moment such that still in each particular case, the investigator should analyse and establish experimentally how important are, relative to each other, the effects 1) and 2) for the activity and the selectivity of a given multimetallic catalyst. It is an historical experience that when the explanation of the data is not immediately obvious, the authors offer as an "explanation" "an electronic (ligand) effect" (7). In this way it happened that the effect sub 1) has been most frequently proven to operate, while the effect sub 2) is the most frequently postulated... [Pg.267]


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See also in sourсe #XX -- [ Pg.192 ]

See also in sourсe #XX -- [ Pg.470 ]

See also in sourсe #XX -- [ Pg.328 ]




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Anionic ligands effects

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Asymmetric ligand acceleration effects

Axial ligand, effect

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Cyclopentadienyl ligand substituent effects

Cyclopentadienyl ligands side ring effects

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Deprotonated ligand effect

Diphosphine ligands, chelating, effect

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Effect of Ligands Already Present

Effect of Organic Ligands

Effect of Quadruplex Ligands

Effect of chiral ligand

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Effective electrochemical ligand parameter

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Effects due to Ligand Exchange in Nickel Complexes

Effects of Ancillary Ligands

Effects of Non-leaving Ligands

Effects of Non-reacting Ligands

Effects of Peptide Ligands

Effects of Several Ligands

Effects of Spectator Ligands

Effects of bases, ligands, and additives

Effects on Ligand-Gated Ion Channels

Effects on the Types of Ligand Bound

Electrocatalysis ligand effect

Electron transfer bridging ligand effects

Enhancement of Ligand Polarisation - Intrinsic Effects

Ensemble and Ligand Effects

Entropic effects, ligand-protein

Entropic effects, ligand-protein interaction

Fischer ligand effect

Halide ligand trans effect

Hydroformylation ligand effects

Hydrophobic Effect of Peptide and Related Ligands

Hydrophobic effect, peptide ligands

Ionic liquids ligand effects

Iron ligand effects

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Ligand Effects for Transition Metal Oxides

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Ligand Effects on the Rate

Ligand acceleration effect

Ligand aryl effect

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Ligand concentration effects

Ligand effect

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Ligand effect on cluster growth

Ligand effect, macrocyclic

Ligand effects Heck reactions

Ligand effects Sonogashira reaction

Ligand effects Stille coupling

Ligand effects Suzuki coupling reactions

Ligand effects and kinetics

Ligand effects in adsorption - changing the d band center

Ligand effects inner-sphere reactions, kinetics

Ligand effects mechanisms

Ligand effects of alloying

Ligand effects on chain length

Ligand effects on chain length Oligomers

Ligand effects on chain length Propanoate

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Ligand effects palladium complexes

Ligand effects with boron enolates

Ligand effects, propene

Ligand electronic effect parameter

Ligand electronic effect, theory

Ligand field effect

Ligand field effects, and reaction

Ligand field effects, and reaction rates

Ligand field stabilization energy, effect

Ligand or Base Effects

Ligand properties, structure, reactivity effects

Ligand structures electronic effects

Ligand substituent effects

Ligand-exchange reaction solvent effect

Ligand-metal cooperative effects

Ligand-receptor interaction-induced functional effects

Ligands catalyst effects

Ligands color effects

Ligands electronic effects

Ligands ligand field effect

Ligands steric effects

Ligands synergistic effects

Ligands, directing effects

Ligands, transition-effecting action

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Luminescence ligand field effect

Macrocyclic ligands electronic effects

Macrocyclic ligands solvation effects

Macrocyclic ligands structural effects

Macropolycyclic ligands structural effects

Metal adsorption ligand effects

Metal ligand effect

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Metal—ligand bonds Jahn-Teller effect

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Palladium complexes effect of ligand size on coordination number

Peptide ligands chelating effects

Phosphine ligands Electronic effects

Phosphorus ligand effects

Platinum complexes effect of ligand size on coordination number

Polyaminocarboxylate ligands, effect

Porphyrins ligand field effects

Protein denaturation, ligand effect

Quantifying Ligand Effects

Quantitative Analysis of Ligand Effects

Reactivity ligand effects

Rhodium carbene reactions ligand effects

Side-Chain Conformation Induced Fit Effects of Ligands

Solubility competing ligand effect

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Spin state ligand effect

Steady ligand concentration effect

Steric effects macrocyclic ligands

Substitution reactions ligand field effect

Sulfur ligands trans effect

Summary of Ligand Effects

Surface ligand effects

The Effect of Bound Ligands

The Ligand Effect

Trans effect hydride ligand

Xantphos ligands, electronic effects

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