Formation and Stability Constants

8 Formation and Stability Constants Table 7 Formation and stability constants 

Formation and stability constants are not presented in detail however, the systems studied and the relevant references are given. 

Schiff bases derived from salicylaldehyde and aniline and its derivatives 941 

Lancaster and W. R. McWhinnie, Inorg. Nuclear Chem. Letters, 1971, 7, 405. 

---

Pb(II) oxalate was studied as well. Complex formation and stability constants were determined by polarography and CV. Results obtained on a solid Pt electrode (C V) confirm measurements obtained previously on DME139. 

X-Ray Data (Copper), Physical Data (Copper), Formation and Stability Constants (Cobalt, Nickel, and Copper)... 

Formation and Stability Constants (Cobalt, Nickel, and Copper)... 

The formation and stability constants of complexes between Pd (Pt. Rh, Ir, Os, Ru) and o-coumaric acid have been determined by pH titration.31 The results indicate that a 1 2 complex is formed with Pd. 

Oxygen Donors. The formation and stability constants oi complexes between Pt (Pd, Rh, Ir, Os, Ru) and o-coumaric acid have been determined by pH titration.31 The results indicate that a 1 2 complex is formed with Pt. Acid-base properties of aquo-complexes formed from [Pt(X)2(OH)2(NH3)(MeNH2)] (X = Cl, Br or N02) in aqueous solutions have been examined using potentiometric titration experiments.186 The Ka of co-ordinated water was lower for (X)2 = (H20)2 than for (X)2 = (H20) (OH-). 

Olofsson, G. (1967) Enthalpies of formation and stability constants for adducts between antimony pentachloride and substituted ethyl acetates. Acta Chem. Scand., 21, 1892-1902. 

Mohamed [63] investigated the complexation behavior of amodiaquine and primaquine with Cu(II) by a polarographic method. The reduction process at dropping mercury electrode in aqueous medium is reversible and diffusion controlled, giving well-defined peaks. The cathodic shift in the peak potential (Ep) with increasing ligand concentrations and the trend of the plot of EVl versus log Cx indicate complex formation, probably more than one complex species. The composition and stability constants of the simple complexes formed were determined. The logarithmic stability constants are log Bi = 3.56 log B2 = 3.38, and log B3 = 3.32 [Cu(II)-primaquine at 25 °C]. 

Af is called a formation or stability constant. Note that the formula for the ion pair, NaQ (aq), symbolizes the interaction of 1 atom of Na with 1 atom of Cl, whereas the representation of crystalline halite, NaCl(s), is an empirical formula in which an imspecified number of Na and Cl atoms are present in a 1 1 stoichiometric ratio. 

Molecular mechanics calculations (MM2(85)) were employed to rationalize the relationship between stmcture and the equilibrium constants of the thiol-disulfide interconversion (Scheme 6) <1990JA6296>. An excellent correlation (r=0.93) between experimental AG values and calculated differences in strain energy A3 if was obtained, AG = 0.41 kj moF and /. SE = 0.5 kj moF thereby supporting the facile formation and stability of 1,2-dithianes. 

The electrochemical properties of Cd(II) complexes with inorganic ligand presented in early papers were discussed by Hampson and Latham [72]. Later, electrochemical investigations of cadmium complexes were oriented on the mechanism of complex formation, determination of stoichiometry and stability constants, mechanisms of reduction on the electrodes, and evaluation of kinetic parameters of these processes. The influence of ligands and solvents on stability and kinetic parameters of electroreduction was also studied. 

The polarographic experimental and calculated curves of complex formation with the following ligands N, Ai -bis(2-pyridyl methyl)- ,2-diaminoethane [118], picolinic acid [119], Ai-(2-hydroxyethyl)ethylenedi-amine [120], 1-hydroxyethylenediphospho-nic acid [121], and Ai-(2-hydroxyethyl)imi-nodiacetic acid [122] was used for modeling the Cd(II)-Kgand systems. The stoichiometry and stability constants of formed complexes were evaluated. The same method was used for determinations of stability constants of Cd(II) complexes with monoaza-12-crown-4 ether in aqueous solution in the presence of an excess of sodium ions [123]. 

The investigation of viscosities, electrical conductivities, refractive indexes and densities of binary liquid systems of sulphuric acid with nitromethane, nitrobenzene and 0-, m and p-nitrotoluene was made in order to obtain a clearer picture of the behaviour of these binary mixtures, regarding the stability of the addition compounds formed between the components. The application of these methods of physicochemical analysis to a number of binary systems with sulphuric acid [1, 2, 3] has enabled us to get some idea of the way in which the formation and stability of addition compounds affects the liquid phase properties of these systems. The binary systems of sulphuric acid with mononitrocompounds are particularly suitable for comparison with each other, because of the close similarity of the liquid media in these systems, due to comparable values of dielectric constants and liquid phase properties of the mononitrocompounds. The stability of the addition compounds in these systems in the crystalline phase [4] has... 

The stepwise constants written for the equilibria above are called formation or stability constants and may be written ... 

The stability and selectivity patterns of cryptands were found to be markedly solvent dependent and stability constants of Ag[2]cryptates in a range of solvents are presented in Table 62.474"478 Thermodynamic data for their formation in water are given in Table 63.476... 

Mixed donor ligands. AG°, AH°, and AS° values for the formation of complexes between asparaginate and Mn2+ as well as H+, Fe2+, Co2+, Ni2 +, and Zn2+ in aqueous solution at 25°C have been reported.93 Cytostatic Hadacidin, JV-formyl-JV-hydroxyglycine (HAD), forms the complex Mn(HAD) for which spectroscopic and stability constant data have been reported.94 Manganese(n) complexes of human serum albumin have also been studied.95... 

Similar to aqueous solutions studies on lanthanide complex formation in non-aqueous solutions involve complex equilibria characterized by equilibrium constants and stability constants which have been discussed in detail in Chapter 3. To recall, we define the equilibrium constants and stability constants as follows ... 

Of course, it is impossible to determine a a priori. If Eq. (17) is physically reasonable, it should be possible to choose a in such a way that a plot of AG (g) — AG°(g) versus DN can be represented by a fairly smooth curve, as shown in Fig. 4 for a s 0.5. This value appears reasonable low a values are highly improbable since the free Cl ion is undoubtedly a much stronger base than the coordinated Cl ion in [CoCl ] on the other hand, solvation enthalpies of the complex anions will compensate only in part, so that a is necessarily < 1. Equation (17) can be used to estimate free energies of formation or stability constants of [CoCl4] in other solvents, provided that the donicities and the values AG(sv)(Cl ) (Table V) are known. Values A( (g) — A( °(g) required for this purpose may be interpolated or extrapolated from Fig. 4. 

---