Formation constant, overall

Hydration enthalpy Stability or formation constant Overall and stepwise stability constants Chelate effect Macrocyclic effect Preorganization Equilibrium template effect Kinetic template effect Self-assembly... 

Each value listed in Tables 8.12 and 8.13 is the logarithm of the overall formation constant for the... 

By convention the displaced water is ignored since its concentration is essentially constant. The overall stability (or formation) constant can clearly be expressed in terms of the stepwise constants ... 

Fig. 12. Titration curves for complexometric titrations. Titration of 60.0 ml of a solution that is 0.02 mol dm-3 in M curve A represents a 0.02 mol dm-3 solution of the tetradentate ligand D to give MD as product curve B represents a 0.04 mol dm-3 solution of the bidentate ligand B to give MB2 and curve C represents a 0.08 mol dm-3 solution of the un-identate ligand A to give MA4. The overall formation constant for each product is 1.0 x 1020. Adapted from ref. 115.

Figure 12 [115] shows a series of complex formation titration curves, each of which represents a metal ion-ligand reaction that has an overall equilibrium constant of 1020. Curve A is associated with a reaction in which Mz+ with a coordination number of 4 reacts with a tetradentate ligand to form an ML type complex. Curve B relates to a reaction in which Mz+ reacts with bidentate ligands in two steps, first to give ML complexes, and finally close to 100% ML2 complexes in the final stages of the titration. The formation constant for the first step is 1012, and for the second 108. Curve C refers to a unidentate ligand that forms a series of complexes, ML, ML2. .. as the titration proceeds, until ultimately virtually 100% of Mz+ is in the ML4 complex form. The successive formation constants are 108 for ML, 106 for ML2, 104 for ML3, and 102 for ML4 complexes. 

Alternatively, a set of overall formation constants may be defined (Table 3.6). 

For convenience these species are often represented by [p, q] and the overall formation constants denoted by /3pq. The degree of protonation of a particular species is given by the ratio q/p. The average degree of protonation of all species in solution, Z, is defined as... 

Assuming unit partition of the uncharged ligand between the equilibrium and interlamellar solution allows one to determine the overall surface complex formation constant g from the... 

Such considerations were extended to metal complexes in 1902 by Morse, who studied the distribution of divalent mercury between toluene and water at various Hg and CT concentrations. By taking complex formation in the aqueous phase into consideration Morse could determine the formation constants of HgCr and HgCb from distribution measurements, as well as the distribution constant of the neutral complex HgCl2. The overall extraction reaction can be written... 

Of the reaction steps, only the first three have values of AG° > 0 however, the large negative value of the fourth step makes the overall reaction AG°x negative, thus favoring the extraction of the complex. The first step can be measured by the determination of the dinitrato complex in the aqneons phase. The second is related to the distribution constant A btbp in the solvent system. Also, the formation constant of the aqneons U02(N03)2(TBP)2 can be measnred (for example by NMR on P of TBP in the aqneons phase). Thns, AG can be derived. 

In Chapter 3 we described how an uncharged metal complex MA is formed from a metal ion central atom) through a stepwise reaction with the anion A (ligand) of a monobasic organic acid, HA, defining a stepwise formation constant k , and an overall formation constant (3 , where... 

Ki stepwise formation constant for ith complex (e.g., MLj) overall extraction constant... 

The reaction between Craq002+ and N02 appears to be the only documented study of the interaction of a superoxometal complex with N02. The 0-0 bond in the product Craq00N02+ is weak and cleaves in the reverse process, the overall formation constant being... 

Table 5. Overall formation constants of Cu(II) complexes with various polymer ligands...

Terms to Understand acid Br0nsted-Lowry base entropy overall formation constant... 

The equilibrium constants, 3 are called overall or cumulative formation constants. The fraction of metal ion in the uncomplexed state, M, can be expressed as... 

Overall (p) and stepwise (K) formation constants were distinguished in Box 6-2. The relation between pn and the stepwise formation constants is... 

The [Ni(CN)4]2 anion is one of the most stable nickel(II) complexes and an overall formation constant as high as about 1030 has been determined.627,62 The structure of the complex is square planar with the nickel(II) bound to carbon atoms of cyanides and with linear Ni—C—N linkages (Table 37).629 630 The planar [Ni(CN)4]2 units are stacked in columns in the crystal lattice with Ni—Ni interlayer distances as short as 330 pm. C-bonded CN- is a strong field donor and the electronic spectrum of [Ni(CN)4]2 shows two weak d-d bands at 444 and 328 nm. 

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