The coordination of Pd(II) with a set of different mercapto and dimercapto
compounds has been investigated by potentiometric titration at 25 degrees C
in KCl 0.1 M. The ligand concentration ranged from 10(-4) M to 10(-3) M, a
nd for each ligand concentration the 0.25, 0.50, 0.75 and 1.00 Metal/Ligand
ratios were examined in the 2.5-11 pH range. Using KCl 0.1 M as an ionic s
trength medium the reported formation constants are implicitly referred to
the complexation reaction starting from [PdCl4](2-) as is generally done fo
r the aquo ion. On the bases of the estimated complexation stoichiometries
some coordination models are proposed. The influence of -SH basicity, total
charge of complexes and steric factors on the coordination properties of t
he various ligands is discussed. (C) 1999 Elsevier Science Ltd. All rights
reserved.