Premium
Interaction of methyltin(IV) compounds with carboxylate ligands. Part 1: formation and stability of methyltin(IV)–carboxylate complexes and their relevance in speciation studies of natural waters
Author(s) -
De Robertis Alessandro,
Gianguzza Antonio,
Giuffrè Ottavia,
Pettignano Alberto,
Sammartano Silvio
Publication year - 2006
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.1012
Subject(s) - chemistry , carboxylate , malonate , ligand (biochemistry) , hexa , medicinal chemistry , carboxylic acid , stability constants of complexes , stereochemistry , inorganic chemistry , ion , polymer chemistry , organic chemistry , receptor , biochemistry
Quantitative data on the stability of mono‐, di‐ and trimethyltin(IV)‐carboxylate complexes (acetate, malonate, succinate, malate, oxydiacetate, diethylenetrioxydiacetate, tricarballylate, citrate, butanetetracarboxylate and mellitate) are reported at t = 25 °C and I → 0 mol l −1 . Several mononuclear, mixed proton, mixed hydroxo and polynuclear species are formed in these systems. As expected, the stability trend is mono‐ > di‐ > trimethyltin(IV) and mono < di < tri < tetra < hexa for the organotin moieties and carboxylate ligands investigated, respectively. Moreover, ligands containing, in addition to carboxylic,OandOH groups show a significantly higher stability with respect to analogous ligands with the same number of carboxylic binding sites. The results obtained from all the systems investigated allowed us to formulate the following empirical predictive equation for correlation between complex stability and some simple structural parameters, 1$$\log \beta = -6.0 + 1.63n_{{{\rm{carb}}}} + 1.4n_{{{\rm{OH}}}} + 4.58r + 3.9z_{{{\rm{cat}}}} $$ where n carb and n OH are the number of carboxylic and alcoholic groups in the ligand, respectively, r is the stoichiometric coefficient of H + (positive) or OH − (negative) and z cat is the methyltin cation charge (CH 3 ) x Sn z + ( z + = 4 − x ). Distribution diagrams for some representative systems are also reported and are discussed in the light of speciation studies in natural waters. A literature data comparison is made with carboxylate complexes of other metal ions with the same charge as the organotin cations investigated here. Copyright © 2005 John Wiley & Sons, Ltd.