Complex Equilibria of Organotin(IV) in Aqueous Solution with Imidazole Derivatives

摘要

Equilibria studies in aqueous solution containing 25% dioxane(V/V)are reported for dimethyltin(IV)and trimethyltin(IV)(M)complexes with some imidazole derivatives(L).Stoichiometry and stability constants for the complexes formed were determined at 25 deg C and ionic strength 0.1M NaNO_3.The results of the dimethylitin(IV)complexes showed the best fit of the titration curves when complexes ML,ML_2,ML_2H~-1,and ML_2H~-2 were expected beside the hydrolysis products of the dimethyltin(IV)cation,while the calculations of the trimethyltin(IV)complexes reported the presence of only the complexes ML,MLH~-1,and the hydrolysis products of the trimethyltin(IV)cation.The concentration distribution of each species of the complexes in solution was evaluated.The stability of all complexes formed was investigated and discussed in terms of molecular structure of the ligand imidazole and the nature of the alkyltin cation.It is deduced that the stability of the complex formed increases as the basicity of the ligand imidazole is increased.On the other hand,the trimethyltin(IV)cation has a very low ability to form complexes compared to the dimethyltin(IV)cation.