
%0 Journal Article
%A Clare, BW 
%A Hefter, G 
%A Singh, P 
%T Zinc(II)-Chloride Complexes in Acetonitrile-Water Mixtures
%J Australian Journal of Chemistry
%D 1990/02/01
%V 43
%N 2
%P 257-261
%K 
%R https://doi.org/10.1071/CH9900257
%U https://www.publish.csiro.au/paper/CH9900257 
%X Equilibrium constants for the formation of ZnCln2-n complexes have been measured in some acetonitrile ( MeCN )-water mixtures ranging from 0 to 100% MeCN at 25&#176;C and I = 0.1 M (Et4NClO4), by potentiometric titration. The equilibria shift strongly in favour of the formation of the higher-order complexes (n = 3, 4) at high MeCN concentrations. This is shown to be due to differences in the magnitude of unfavourable solvation of the Zn2+, Cl - and ZnCln2-n ions in MeCN-H2O solutions. The Gibbs free energies of transfer of all of these ions from water to MeCN-H2O mixtures are strongly positive, but the net change in the transfer function for the formation of the higher-order complexes is favourable. Thus the formation of these complexes is predominant in MeCN -rich aqueous solutions. Approximate measurements in propiononitrile indicate that the ZnCln2-n complexes are even stronger than in acetonitrile. 
