Metal-ligand formation constants

Conditional Metal—Ligand Formation Constants Recognizing EDTA s acid-base properties is important. The formation constant for CdY in equation 9.11 assumes that EDTA is present as Y . If we restrict the pH to levels greater than 12, then equation 9.11 provides an adequate description of the formation of CdY . for pH levels less than 12, however, K overestimates the stability of the CdY complex. 

A difference plot, also called a Bjerrum plot, is an excellent means to extract metal-ligand formation constants or acid dissociation constants from titration data obtained with electrodes. We will apply the difference plot to an acid-base titration curve. 

The binding constants (illustrated here as metal-ligand formation constants) may be either stepwise formation constants (equation 22-1) or cumulative formation constants Pn (equation 22-2). Charges have been omitted for clarity. 

The value of ai will depend on the formation constants of the metal ion-ligand formation constants, the concentration of excess ligand in the mobile phase and the pH. Calculation of Oi according to Ringbom [12] follows the equation ... 

The table summarizes the data up to the end of 1972. For each extractant and Its extractable metal complexes, distribution equilibrium constants, as well as appropriate extraction constants, are recorded. In addition, the homogeneous equilibria involving the acid dissociation of the extractant in the aqueous phase and adduct or mixed ligand complex formation in the organic phase are characterized. Aqueous phase metal complex formation constants however, are not included inasmuch as these are already covered in Stability Constants. 

Metal-complex formation constants may be determined through NMR by observing the pH-dependency of certain proton chemical shifts in solution composed of the organic ligand and a non-paramagnetic metal ion. 

Metal ion-ligand formation constants are listed in Tables 8-2, 9-1, and 9-2. Redox potentials are found in Table 12-1. 

Similar curves were obtained for racemic and L-polypropyleneglycine, PICEI and PEA. At high ligand concentration n approaches the limiting value of 2. Taking account of the presence of two coordinating atoms in each monomer unit, the coordination number four is thus found from the experimental data. Table IV summarizes the metal complex formation constants for the different poly ampholytes. The displacement constant B2 is defined by the equation... 

TABLE 8.12 Cumulative Formation Constants for Metal Complexes with Inorganic Ligands... 

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