Complex Formation Reactions of Dimethyltin(IV) with Some Zwitterionic Buffers

Equilibrium Studies of Dibutyltin(IV)-Zwitterionic Buffer Complexation

Equilibrium studies in aqueous solution are reported for dibutyltin(IV) (DBT) complexes of the zwitterionic buffers “Good’s buffers” Mes and Mops. Stoichiometric and formation constants of the complexes formed were determined at different temperatures and ionic strength 0.1 mol·L⁻¹ NaNO₃. The results show that the best fit of the titration curves were obtained when the complexes ML, MLH₋₁, MLH₋₂ and MLH₋₃ were considered beside the hydrolysis product of the dibutyltin(IV) cation. The thermodynamic parameters ΔH^o, ΔS^o and ΔG^o calculated from the temperature dependence of the formation constant of the dibutyltin(IV) complexes with 2-(N-morpholino)ethanesulfonic acid (Mes) and 3-(N-mor-pholino)-propanesulfonic acid (Mops) were investigated. The effect of dioxane as a solvent on the formation constants of DBT–Mes and DBT–Mops complexes decrease linearly with the increase of dioxane proportion in the medium. The concentration distribution of the various complexes species was evaluated as a function of pH.

Complex formation reactions of lanthanum(III), cerium(III), thorium(IV), dioxouranyl(IV) complexes with tricine

Equilibrium studies for the heavy metal ions La(III), Ce(III), Th(IV) and UO2(IV) (M) complexes of the zwitterionic buffer tricine (L) in aqueous solution are investigated. Stoichiometry and stability constants for the different complexes formed as well as hydrolysis products of the metal cations are determined at 25 degrees C and ionic strength 0.1 M NaNO3. The stability of the formed complexes are discussed in terms of the nature of the heavy metal cation. The solid complexes are synthesized and characterized by means of elemental analysis, FTIR, and TG analysis. The general molecular formulae of the obtained complexes is suggested to be [M(L)2](NO3)n-2(H2O)x, where n = the charge of the metal cation, x = no. of water molecules.