Formation Constant of Dialkyltin(IV)-N-(Alkyl)-2/3-mercaptoacetamide Systems

The thermodynamic formation constants of N-(alkyl)-2- and/or 3-mercaptoacetamides complexes with dimethyl-, diethyl-, and n-dibutyltin(IV) cations have been determined potentiometrically in a dioxane-water mixture (75% v/v) at 30 ± 0.1°C in μ = 0.1 M NaCl using the Irving-Rossotti method and refined by the least-squares method. The basicity of the ligands follows the order C₂H₅NHCOCH₂SH > n-C₃H₇NHCOCH₂SH > n-C₄H_gNHCOCH₂SH > C₂H₅NHCOCH₂CH₂SH > n-C₃H₇NHCOCH₂CH₂SH > n-C₄H_g- NHCOCH CH SH. For each ligand the stability order of dialkytin(IV) complexes decreases as follows: Me₂Sn(IV)]²⁺ >Et Sn(IV)]²⁺ > n-Bu₂Sn(IV)]^2+. This order is consistent with the group electronegativities of R₂Sn(IV)]²⁺ cations calculated from Sanderson's electronegativity scale.