Activation of ligands

Using a chiral diphosphine Rh(I) complex as the catalyst, high catalytic activity and a good branched/linear ratio can be achieved, but in most cases the ee values remain moderate.122 The enantioselectivity of Rh(I)-catalyzed reactions depends on the amount of added chiral ligand because of the much higher catalytic activity of ligand-free rhodium species. Usually 4 6 equivalents... 

We carried out some measurements some years ago in order to measure the transfer coefficient in DMF for this couple at a mercury electrode [Hush, N. S. Dyke, J. M. J. Electroanal. Interfac. Electrochem. 1974, 53, 253]. The deviation from one-half for the value so obtained was consistent with reasonable values for the free energy of activation of ligand exchange in the inner-coordination spheres. 

To investigate the origin of the very high hydroformylation and isomerization activity of ligand 33, we measured the rate of CO dissociation from the HRh(dipho-sphine)(CO)2 complex using labeling in rapid-scan IR experiments [54]. The CO dissociation rate constants, ki, can be obtained by exchanging CO for CO in the HRh(diphosphine)( CO)2 complexes [52].The CO dissociation proceeds via a dissociative mechanism and consequently obeys simple first-order kinetics. The rate constants kj can, therefore, be derived from Eqs. (5) and (6). 

Kersey FR, Yount WC, Craig SL. Single-molecule force spectroscopy of bimolecular reactions system homology in the mechanical activation of ligand substitution reactions. J Am Chem Soc 2006 128 3886-3887. 

IN VIVO BIOLOGICAL ACTIVITIES OF LIGANDS IN ANIMAL MODELS... 

Gk, the activator of ligand-gated K+ channels mechanism of muscarinic regulation of atrial pacing... 

Figure 3.5 Activation of ligands in transition metal chemistry.

Key reactions include (a) substitution (b) electron transfer (c) activation of ligands (d) redox-catalyzed substitution (e) oxidative-addition reaction (f) insertion (g) redox-catalyzed insertion. 

C) Redox-catalysed substitution proton transfer activation of ligands... 

The pseudo-receptor concept has been applied in recent years to analyze crucial ligand-receptor interaction sites and to establish 3D-QS ARs for the prediction of biological activities of ligands. A variety of application studies have shown that the pseudo-receptor concept is a versatile tool to establish 3D-QSAR models, often better in their predictive behavior compared to results obtained from classical 3D-QSAR approaches (e.g. CoMFA). Several application studies have been published which have shown the value but also the limitations of this approach. ... 

Takemori AE, Suitana M, Nagase H, et al. Agonist and antagonist activities of ligands derived from naitrexone and oxymorphone. Life Sci 1992 149 1-5. 

If the metal ions can be reduced to the metal, which means that all ligands will be stripped off during this reduction, the following equation can be derived [6] for the dependence of the half-wave potential (which is equal to Ef ) on the activity of ligands An" and the stability constant of the complex K ... 

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