Spectrophotometric and potentiometric study on platinum(II) chelates of mercapto carboxylic acids

Citation
G. Crisponi et al., Spectrophotometric and potentiometric study on platinum(II) chelates of mercapto carboxylic acids, POLYHEDRON, 19(24-25), 2000, pp. 2435-2440
Citations number
16
Categorie Soggetti
Inorganic & Nuclear Chemistry
Journal title
POLYHEDRON
ISSN journal
02775387 → ACNP
Volume
19
Issue
24-25
Year of publication
2000
Pages
2435 - 2440
Database
ISI
SICI code
0277-5387(20001130)19:24-25<2435:SAPSOP>2.0.ZU;2-#
Abstract
The coordination of Pt(II) with different mercapto and dimercapto compounds has been studied using both potentiometric titration at 25 degreesC in KCl 0.1 M and UV-Vis spectroscopy. The slow complex formation kinetics has bee n followed spectrophotometrically for several days on samples with differen t ligand molar fractions ranging from 0.1 to 1, keeping the ligand and meta l concentration below 8 x 10(-4) M. For the potentiometric titration, the l igand concentrations were kept constant at 10(-3) M, and the 0.25, 0.5, 0.7 5 and 1.00 metal/ligand ratios were titrated in the pH range 2.5-11 for eac h ligand. The solutions were kept in a thermostatted bath at 25 degreesC fo r 2 days before titration. The stabilization of the absorbance values under these conditions after 2 days, and the back titration with hydrochloric ac id 0.1 M, led us to conclude that the proper equilibrium complex formation is reached under these conditions. Using KCl 0.1 M as an ionic strength med ium, the reported formation constants are referred to the complexation reac tion starting from [PtCl4](2-). Some models are proposed on the basis of th e estimated stoichiometries. (C) 2000 Elsevier Science B.V. All rights rese rved.