
%0 Journal Article
%A Livingstone, SE 
%A Sullivan, EA 
%T Thio derivatives of &#946;-diketones and their metal chelates. XI. Stability constants of nicke(II), copper(II). zinc(II), cadniium(II), and lead(II) chelates of two monothio-&#946;-diketones
%J Australian Journal of Chemistry
%D 1969/07/01
%V 22
%N 7
%P 1363-1379
%K 
%R https://doi.org/10.1071/CH9691363
%U https://www.publish.csiro.au/paper/CH9691363 
%X The acid dissociation constant (pKD) of the monothio derivative of benzoyl-acetone, viz. 3-mercapto-1-phenylbut-2-en-1-one (I), was found to be 10.43 in 74.5 vol. % dioxan-water solution. Stoicheiometric stability constants (log kn) of five metal chelates of (I) and of the monothio derivative of dibenzoylmethane, viz. 3-mercapto-1,3- diphenylprop-2-en-1-one (II), have been measured in 74.5 vol. % dioxan- water solution with both chloride and perchlorate as supporting electrolyte.     With chloride as supporting electrolyte the values obtained for log kav are as follows: with ligand (I), copper(II) 10.11, nickel(II) 9.25, zinc(II) 6.68, lead(II) 6.06, cadmium(II) 6.12; with ligand (II), copper(II) 10.66, nickel(II) 10.20, zinc(II) 7.44, lead(II) 7.11, cadmium(II) 6.90. With perchlorate as supporting electrolyte zinc, lead, and cadmium give values of log kav which are 1.5-1.9 units greater. The thermodynamic stability constants (logKn) were calculated from the stoicheiometric constants by use of the equations              Log K1 = logk1 + 2.30        logK2 = log k2 + 1.15  For the copper and nickel complexes of both (1) and (II) log Kav is greater than pKD; such a situation has been reported in only a few instances.     From the data obtained with chloride as a supporting medium, approximate stoicheiometric stability constants were calculated for the chloro complexes MCl+ (M = Zn, Cd, Pb) in 74.5 vol. % dioxan. The values obtained were: ZnCl+, 5.0; CdCl+, 5.7; PbCl+, 5.0. 
