Metal Complex Formation Constants

Polyaza macrocycles with pendant arms have been stndied extensively, in particular with respect to protonation and complexation as well as to the kinetics of metal complex formation. These aspects are treated in a review by Kaden. Of particular interest is the fact that metal complex formation constants of macrocycles with pendant carboxylates can be 10 to 10 times higher than for the unsubstituted analogs. 

Zucconi TD, Janauer GE, Donahe S and Lewkowicz C, Acid dissociation and metal complex formation constants of penicillamine, cysteine, and antiarfiiritic gold complexes at simulated biological conditions,/. Pharm. Sci, 68(4), 426-432 (1979). 

Equilibria involving protons are written as stability constants (protonation constants) rather than as Ionization constants to be consistent with the metal complex formation constants. Consequently the A H and AS values have signs opposite to those describing ionization constants. 

APPENDIX B. METAL COMPLEX FORMATION CONSTANTS. B-a. LOG Pj INORGANIC COMPLEXES, continued... 

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. 

This 228 page volume summarizes equilibrium constants for liquid-liquid distribution equilibrium constants up to the end of 1972. Each table includes the extractant and its extractable metal complexes, and.the distribution equilibrium constants and extraction constants. The aqueous phase metal complex formation constants are not included and the reader is referred to items and in this bibliography for sources of this type of data. References to the primary literature are included. 

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... 

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