Polarographic and spectrophotometric study of lead complexes with diethanoldithiocarbamate

Abstract

Experimental and theoretical aspects concerning the behaviour of lead-dietanoldithiocarbamate complexes in aqueous solutions were studied. The reaction occurs through complexation and formation of a yellow precipitate, which is soluble in ligand excess and in some polar solvents. The results from elementary and gravimetric analyses show a stoichiometric relationship of 1:2 (Pb(II): DEDC). Some ambiguous interpretations have been clarified on the application in this system of Lingane's equation. Polarographic measurements were used to determine the coordination number (≅ 3.0) and overall formation constant βMLn(≅ 4 × 1016), of the lead complexes with ammonium diethanoldithiocarbamate, which show a good agreement with previous potentiometric results for the same system. A kinetic-spectrophotometric study was carried out in order to establish the decomposition of these complexes in acid medium.