Interaction of Alkyltin(IV) Compounds with Ligands of Interest in the Speciation of Natural fluids: Complexes of (CH3)2Sn2+ with Carboxylates

Abstract

Complex formation by (CH3)2Sn 2+ with acetate (ac), malonate (mal), 1,2,3-propanetricarboxylate (tricarballylate, tca) and 1,2,3,4-butanetetracarboxylate (btc) ligands in aqueous solution is reported. The study has been performed by potentiometry ([H + ]‐glass electrode) at T = 25 °C, and in the 0 < I < 1 mol dm 2 3 ionic strength range. In order to evaluate the salt effects on the formation constants of the complex species, and to contribute to the definition of the chemical speciation of diorganotin(IV) compounds in natural waters where carboxylic ligands are naturally present, interactions of NaCl (which is the major component of all natural fluids), with the components of the systems under investigation have also been considered. A model for the ionic strength dependence of the formation constant was used in order to calculate the values of thermodynamic constants, at infinite dilution, for all the proposed species, by considering hydrolytic species too. A relationship between the charges on the different ligands considered and the stabilities of the complex species formed is also discussed. © 1997 by John Wiley & Sons, Ltd.