Equilibrium and spectroscopic studies of diethyltin(iv) complexes formed with hydroxymono- and di-carboxylic acids and their thioanalogues

The complex formation of diethyltin(IV) cation with glycolic (GA), lactic (LA), succinic (SA), malic (MA), tartaric (TA), mercaptoacetic (MAA), 2-mercaptopropionic (MPA), mercaptosuccinic (MSA) and dimercaptosuccinic acid (DMSA) has been investigated by potentiometric, spectrophotometric, 1H NMR and Mossbauer spectroscopic methods. The mercaptocarboxylic acids yielded much more stable complexes than the corresponding hydroxy acids. Below pH 3, the carboxylate and the still protonated hydroxyl group of hydroxy acids are co-ordinated to the metal ion, while in the case of their thio analogues, {COO−, S−} co-ordinated species are dominant. With increasing pH, the metal promoted deprotonation o…