Dimer and Trimer Formation in Ionic Solution

COMPUTATIONS OF DIMER AND TRIMER FORMATION IN IONIC SOLUTION 

In forming post-2000 theories of solutions, it is important to know what fraction of the ions in a solution are associated to form dimers and ttimers and perhaps higher aggregates. Dimers are not charged and will interact with the surrounding ions as 

Experimental methods for determining dimer formation were published in an early book (Davies, 1962). The author interpreted conductance data in terms of degrees of association. His book had less impact than might have been thought reasonable because of ambiguities arising from allowance of the parallel effects of interionic attraction, as well as ion association to dipoles, in lowering equivalent conductance as the concentration increased. 

One might suspect that Raman spectra would give an indication of ion pairs, but this is only tme for pairs (such as those involving NO where the ion pairing affects a molecular orbital (such as that in N-O). In a pair such as Na Cr, there are no chemical bonds—and it is these that produce spectra—so that ion pairs may exist without a spectral signature. 

It follows that experimental determination ofion pairing has been difficult to carry out. Some theoretical works by Wertheim (1984) have contributed a correlation function approach to ion pairing that improves on the original work by Bjerrum (1926). The major difference is the form of the interaction energy between the ions, Uy g-. In 

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