TRIPROPYLTIN(IV) COMPLEXES WITH SOME SELECTED BlO- LIGANDS IN 50% V/V DIOXANE/WATER MIXTURE.

The interaction of the tri-n-propyltin(IV) (TPT) with some selected bio- ligands having a variety of model functional groups were investigated using potentiometric technique at 25°C and 0.1 M ionic strength in 50% v/v dioxane/water mixture. TPT is hydrolyzed to give [(C₃H₇)₃SnOH], [(C₃H₇)₃Sn(OH)₂], and [((C₃H₇)₃Sn)₂OH]⁺. Amino acids and DNA constituents form 1:1 and 1:2 complexes. Peptides form 1:1 complexes and the corresponding deprotonated amide species. The protonated complexes are formed with amino acids, peptides and some DNA constituents. The hydrolysis constants and the stepwise formation constants of the complexes formed in solution were calculated using the nonlinear least-square program MINIQUAD-75. The participation of different ligand functional groups in binding to organotin is discussed. The speciation diagrams of the various complex species were evaluated as a function of pH. [ABSTRACT FROM AUTHOR]