Organic ligand complexes stability constants

Martell, A. E. 1964. Section II Organic ligands in stability constant of metal-ion complexes. Special Publication 17. London The Chemical Society. 

Important selectivity enhancements are observed upon complexing with neutral ligands. The stability constants of the adsorbed complexes exceed the values in aqueous solution by two to three orders of magniture. Such observation may be relevant to the behaviour of transition elements in the environment in that stability constants of adsorbed organic matter complexes may differ from the values found for solution phase equilibria. Such effects are indeed observed for Cu (139) and Ca (132). 

Formally, complexation stability constants in water (log K) and extraction constants (logA j.J can be related via partitioning coefficients of the free ligand and its complex between the aqueous and organic phases.16 However, the latter are rarely available, and therefore the relationships between log/f and log Ktx are not widely used. Nevertheless, in many cases, the binding ability of ligands to metal in complexation and extraction processes follows the same trend. In this respect, information... 

Rossotti et al [Fa 70] found that the ratio of stability constants obtained by equilibrium measurements in solvent mixtures similar to the above was independent of the composition of the solvent. McBryde et al showed that in most of the systems they examined, the ratio of the first two stepwise complex stability constants did not depend on the solvent. In the case of the stepwise acid dissociation constants this correlation was approximately true only for ethylenediamine for glycine the ratio of the protonation constants increase with increase in the concentration of the organic component. However, if the formation of the glycine complexes is defined as a reaction between the protonated ligand and the metal ion, accompanied by the liberation of a hydrogen ion, the ratio of the equilibrium constants is approximately independent of the composition of the solvent mixture. 

L. G. SiLLfiN and A. E. Martell, Stability Constants of Metal-ion Complexes, The Chemical Society, London, Special Publications No. 17, 1964, 754 pp., and No. 25, 1971, 865 pp. Stability Constants of Metal-lon Complexes, Part A. Inorganic Ligands (E. Hcigfeldt, ed.), 1982, pp. 310, Part B. Organic Ligands (D. Perrin, ed.), 1979, pp. 1263. Pergamon Press, Oxford. A continually updated database is now provided by L. D. Pettit and K. J. Powell (eds.), IVPAC Stability Constants Database, lUPAC and Academic Software. 

Furia, T. E. (1972). "Sequesterants in Foods," Chapter 6 in CRC Handbook of Food Additives, 2nd ed. CRC Press, Boca Raton, FL. Comprehensive tables of stability constants for many complexes of organic and biochemical ligands of metals. 

Perrin, D. D. Stability Constants of Metal-Ion Complexes. Part B Organic Ligands , Pergamon Press Oxford, 1979. 

Copper may exist in particulate, colloidal, and dissolved forms in seawater. In the absence of organic ligands, or particulate and colloidal species, carbonate and hydroxide complexes account for more than 98% of the inorganic copper in seawater [285,286]. The Cu2+ concentration can be calculated if pH, ionic strength, and the necessary stability constants are known [215,265-267]. In most natural systems, the presence of organic materials and sorptive surfaces... 

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