Cumulative stability constant

The corresponding (thermodynamic) stability constant K and the (thermodynamic) cumulative stability constant (P) are, according to Sillen and Martell (1964, 1971), defined as ... 

Hydrolysis and, more generally, complex formation equilibria may be described by cumulative stability constants, Using the Equations (3.28)-(3.31)... 

Figure 7. Cumulative stability constants for some Fe(III) complexes and solids at I = 0, plotted against the constants for corresponding Al(lll) complexes and solids. The dashed line is drawn for reference through equal log values for...

The product of the consecutive stability constants is the cumulative stability constant, p ... 

The cumulative stability constants for the formation of the homobinuclear helicates with the seven ligands H2L13 are reported in Table 8 and a t) ical distribution diagram is represented on Figure 99 for ligand... 

TABLE 20 Cumulative stability constants reported for the formation of mononuclear and homometallic binuclear complexes in acetonitrile solution (spectrophotometric titration of Lk or [M(L/c)3]" 10 M)... 

The constant of this equilibrium is called the overall or cumulative stability constant of the MX Y W" complex. The quantitative expression for cumulative stability constant, can be greatly simplified by removing those terms that are constant. The number of water molecules attached to each metal ion is constant. In dilute solutions, the concentration of water is effectively constant. Then, the equation written without indicating molecules of the solvent becomes ... 

It should be noted that cumulative stability constants characterize complete dissociation of the complex compound. It is clear that the equilibria, representing the... 

To account for the distribution of system components, we used the material balance equations described in Chapter 1. Appropriate stabiUty constants selected from the reference books [1] are listed in Table 8.4. Cumulative stability constants P and refer to the complete dissociation of CuL and species. 

Constants of these equilibria are simply cumulative stability constants of the species given on the right side of Eqs. (9.3)-(9.5) and respectively). 

Table 9.1 Cumulative stability constants of Sn(ll) and Co(ll) citrate complexes used in simulations.

Table 9.4 Cumulative stability constants of Co(ll) and Mo(VI) citrate complexes.

Polarographic methods were used by Frost et al. ° to determine the cumulative stability constants (/ four ligands would be represented as Pt) of substituted thiourea derivatives with Cu(l) in acid. Values for p4 that were greater than 10 were determined for thiourea, hexahydropyrimidine-2-thione, and several other complexes with Cu(l). These very high stability coefficients in acid explain the abiiity of these iigands to prevent copper from plating onto steel in HCI at acid concentrations >1 M. 

For many purposes the cumulative stability constant (P) is required this is the product of the individual constants. If there are two individual constants, the product is designated P if there are three constants, P3. Stability constants are usually determined by potentiometric (glass electrode) titration of the ligand, in the presence and absence of the metal, and the results are processed by a set of rather complex calculations for which a computer programme can conveniently be used. 

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