Ligand mixtures

The solution of the ligand mixture (solvent in square brackets, [ ]) was added to the solution of the precursor (solvent in braces, ), and the reaction mixture was stirred for 10-30min. 

These problems would be encountered even in relatively simple systems containing a mixture of characterized, synthetic ligands. The situation is considerably more complicated in natural systems containing a multicomponent ligand mixture. Frequently, when dealing with such cases, the total number of ligand species, or their individual nature and concentration may not be known. 

Consider the continuous addition of a single metal species to a ligand mixture represented by ELi where the total volume of the solution is maintained constant i.e. a metal-into-ligand batch titration. The following scheme with mononuclear complexes, including mixed ligand species, illustrates the reactions which can... 

Case 2. In this case a four-ligand mixture (Table III) is considered, where only 1 1 complexes form. In addition, absorp-tivities are assigned to each of the complex species in order to obtain an absorbance surface. Unlike Case 1, none of the numerical values used in Case 2 (stability products, absorptivities, etc.), while realistic, correspond to any specific, real system. 

Figure 4. Various surfaces relating to the four-ligand mixture described in Table III (a), (b)y and (c) are the stability (Si), free metal (pM), and absorbance surfaces, respectively at pH 7.0. Plots (d), (e), and (f) are the contour diagrams corresponding to (a), (b), and (c), respectively. Note that surface (c) is being viewed from a different direction compared with (a) and (b). The arrows on the contour maps (d), (e), and (f) indicate the corners from which the corresponding perspective representations (a), (b), and (c) are being viewed.

Simplified presentation of Equations 2, 4, 6, 9 and 11. Equations 2, 4, 6, 9 and 11 of this paper may appear somewhat abstract and complicated. This is simply because they are written in a general mathematical format which incorporates mixed ligand in addition to the homogeneous complexes. The meaning of these equations can be clarified by means of a specific example consider the S2 function for a simple two-ligand mixture (from eqn. 2). The only 1 2 complexes in this system are M(L1), M(L1)(L2) and M(L2)2. Thus, ... 

MacCarthy, P. and Smith, G.C., Metal-binding by ligand mixtures a quantitative model, jri Hemphill, D.D., ed., Proc. 

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