Ligand exchange equilibrium

The binding and release of oxygen by hemoglobin can be represented as a ligand-exchange equilibrium at the sixth coordination site on the Fe ion. Each of the four polypeptide chains of hemoglobin contains one heme unit, so... 

The phosphoranes (14) readily undergo ligand exchange on treatment with organolithium reagents. Thus, (14 R = Ph) with butyl-lithium gave an almost quantitative yield of (14 R = Bu) whereas with the less basic methyl-lithium equilibrium was established between (14 R = Ph) and (14 R = Me). 

Ligand exchange Equilibrium Chromatographic separation of glucose-fructose mixtures with Ca-form resins Removal of heavy metals with chelating resins Affinity chromatography... 

Ligand exchange reactions of the zinc complexes are quite rapid (Scheme 4). The equilibrium concentrations of the individual species are attained within the time scale of sample preparation (i.e. <2 min). 

Scheme 5.3 Schematic representation of the ligand-exchange equilibrium.

The larger bite angles of the C3-bridged ligands preclude the ligand-exchange equilibrium, the ionic radius of the nickel(II) ion being too small to accommo-... 

In any case, exceptions to the FIAM have been pointed out [2,11,38,44,74,76,78]. For example, the uptake has been shown to depend on the Cj M or rMI (e.g. in the case of siderophores [11] or hydrophobic complexes [43,50]), rather than on the free c M. Several authors [11,12,15] showed that a scheme taking into account the kinetics of parallel transfer of M from several solution complexes to the internalisation transporter ( ligand exchange ) can lead to exceptions to the FIAM, even if there is no diffusion limitation. Adsorption equilibrium has been assumed in all the models discussed so far in this chapter, and the consideration of adsorption kinetics is kept for Section 4. Within the framework of the usual hypotheses in this Section 3, we would expect that the FIAM is less likely to apply for larger radii and smaller diffusion coefficients (perhaps arising from D due to the labile complexation of M with a large macromolecule or a colloid particle, see Section 3.3). 

As shown for 65 and 66 in Scheme 16, compounds of this particular formula type can also undergo an intermolecular ligand exchange in solution ([D6]DMSO, room temperature detection of the thermodynamic equilibrium 65 + 66 2 76).47 However, this ligand exchange is significantly slower than the intramolecular (A)/(A)-isomerization mentioned earlier. 

Fig. 9.11 a) Chemical structures of MMB and TFMB. b) Possibilities to reduce the total dipole moment in a SAM of mercaptobiphenyls by interactions with a polar solvent, tilt or assembly of opposite dipoles in mixed monolayers, c) Surface versus solution composition found for MMB and TFMB mixed systems in polar (ethanol) and less polar (toluene) solutions illustrating the effect of the assembling dipoles, d) The opposite molecular dipoles of MMB and TFMB proved to be sufficient to induce ligand exchange in order to reach an equilibrium situation in the surface composition (modified from ref [96]). 

A quite unique approach is also the complexation of chiral olefins by a ligand exchange type reaction with the chiral platinum(lV) complex (Table 1, entry 57). It is an equilibrium... 

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