Formation constant, of complexes

Table 15.4 lists formation constants of complex ions. In each case, Kt applies to the formation of the complex by a reaction of the type just cited. Notice that for most complex ions listed, Kf is a large number, 10s or greater. This means that equilibrium considerations strongly favor complex formation. Consider, for example, the system... 

Equations for the evaluation of formation constants of complexed ion species in cross-linked and linear polyelectrolyte systems. J. A. Marinsky, Ion Exch. Solvent Extr., 1973,4, 227-243 (18). 

L. G. Sillen, A. E. Martell, Stability Constants of Metal-Ion Complexes, Spec. Publ. 17 and 25 (Supplement 1), The Chemical Society, London, 1964, 1971 contain data on formation constants of complexes with references to the original literature. 

It is assumed that the formation constants of complexes H and L are very large + denotes that the rate constant is finite... 

Hetaeric chromatography, 230, 231 effect of charge on hetaeron, 233 retention model of, 231-238 Hetaeron. 191, 230, 231, 240, 243, 249, 280 see also Complexing agent adsorption on the stationary phase, 231, 249,230 amphiphilic, 243 cetrimide, 248 decylsulfonate, 230 dodecylbenzenesulfonate, 230 formation constant of complexes, 276 lauryl sulfate, 230 metal chelating, 262 micelle formation, 230 optically active, 262 surface concentration of, 232... 

B) The AG -values derived from formation constants of complexes in methanol (cf. Table 2) are not identical with the free energies of transfer AG, as defined by Eq. (30), because the cations are already solvated by the nonaqueous solvent prior to the complexation. These values are representative, none the less, since the solvation of cations in water and methanol is very similar (95). 

The obvious first step in checking for the consistency of the data is comparing equilibrium constants of cations with the same charge and similar ionic radius. Comparison of the formation constants of complexes and solids of tet-ravalent actinides (Th, U4+, Np4+, Pu4+), Zr4+, and Sn4+ reveals that the selected data are very similar, which is to be expected from a chemical point of view, and none of the formation constants appears to be improbable (for details see Hummel et al. 2002). Similar pictures of chemical consistency emerge from the triva-lent Np3+, Pu3+, Am, and Eu3+ complexes and solids, and from the hexavalent UOz"1", NpOl4, and PuO complexes and solids (Hummel et al. 2002). 

Formation constants of complexes between aromatic electron donors and di-n-propyltetrachlorophthalate in an inert solvent (class A(ii)) have been measured. The complex formation constant is obtained from the following equation ... 

A fairly recent development in zinc and cadmium chemistry has been the use of NMR to study the coordination environment of these metals 1L1Cd, 113Cd and 67Zn nuclei have been A structure-reactivity relationship which predicts formation constants of complexes with organic ligands has been put forward.241 ... 

They are often plasticized PVC matrices, which occlude an ionophore as the key selective element, a chromoionophore or a fluoroionophore as the chemical-optical transducer and, sometimes, ionic additives to maintain electroneutrality. Such optodes follow ion-exchange mechanisms between the membrane and the aqueous solution and the analytical response originates from the ratio of the concentration of ions in the solution or from their product (Fig. 3). Moreover, selectivity is ruled by the ion distribution coefficients between both phases and by the formation constants of complexes within the membrane. 

TAM, spectrophotometrie determination of vanadium photometric determination of niobium in the presence of triethanolamine spectrophotometrie determination of bismuth in the presence of 1,3-diphenylguanidinc spectrophotometrie determination of yttrium in the presence of 7.ephiramine formation constants of complexes with Infill) measured... 

The cations Mg2+ and Ca2+ can be solvated by acetone, methanol, MeCN, HMPA, THF, and other ethers. In aqueous solutions the formation constants of complexes vary enormously and depending on the choice of ligand high selectivity for a particular ion can be obtained. These are the main trends ... 

D. DeFord and D. N. Hume, The Determination of Consecutive Formation Constants of Complex Ions from Polarographie Data, J. Am. Chem. Sot 73 5321 (1951). 

Another approach to the assessment of ion speciation in the resin and solution phases with equal ility for the determination of formation constants of complexes in these two environments is provided by NMR spectroscopy. The method can provide sharp, well-separated signals for each successive complex species formed, the peak area being proportional to the atomic concentration of the element being measured, irrespective of its complex form. For a completely labile system, a well-defined chemical shift change is often observed with successive complex formation. These features make this analytical procedure well suited for study of metal ion complexation by the ion-exchanger phase. 

Studies on ionic hydration and complex formation reactions in solution in the 1960 s quite actively proceeded in Europe, especially in northern Europe. J. Bjerrum, a son of N. Bjerrum in Denmark, established a method for determination of stepwise formation constants of complexes with simple monodentate ligands in solution by the spectrophotomeffic method, which was soon modified to the method by potentiometry. Sillen in Sweden extended the method to polynuclear complex formation reactions and Schwartzenbach in Switzerland, who is a pioneer of chelate chemistry, applied this method to multidentate ligand complexes... 

The work of Irving and da Silva (16) shows how extensive a series of univalent pseudo-metal ions is available. These workers measured formation constants of complexes of ethylmercury(I), dimethylthallium(III), and uramil-7,7 -diacetic acid (R = R = H) and the 1-methyl- and 1,3-dimethylhomologs. 

There seems to be no reason why equations such as (49), (50) and (51) should not be extended to other processes, such as redox potentials and formation constants of complexes in DMF and methanol (Parker, 1966). Correlation of behaviour in water and in protic solvents other than methanol, with behaviour in dipolar aprotic solvents such as DMAC, DMF, DMSO and acetonitrile is an obvious extension, using appropriate constants in equations corresponding to (49), (50) and (51). 

Understand the conventions and algebraic relations among mass-balance equations and stepwise and cumulative formation constants of complexes. 

Marsicano, E, and R. Hancoc k. 1978. The linear free energy relation in the thermodynamics of complex formation, 2. Analysi.s of the formation constants of complexes of the large metal ions Ag Hg- and Cd with ligands having soft" and nitrogen-donor atoms. J. Chem. Soc. Dalton 1978 228-34. 

There are not enough comparable data to put many metal ions in rank order, but the following orders of decreasing values of —A// can be established Hg Cd2+ > Zn2+ Pt Pd > Ni2+. Also the Irving-Williams order for formation constants of complexes, < Cr > Mn < Fe < Co <... 

DEF/HUM] DeFord, D. D., Hume, D. N., The determination of consecutive formation constants of complex ions from polarographic data, J. Am. Chem. Soc., 73, (1951), 5321-5322. Cited on page 431. 

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