Sulphonamide nitrogen-containing N-protected amino acids interacting with palladium(II). Polarographic and pH-metric investigation in aqueous solution

Abstract

The interaction of N-benzenesulphonyl-, N-tosyl-, and N-dansyl-glycine (dansyl = 5-dimethyl-aminonaphthalene-1-sulphonyl) with Pd^II in aqueous solution was investigated by electrochemical methods. In the pH range 4–11.5 all ligands give rise to the species [Pd(LNO)] and [Pd(LNO)₂]^2–(LNO = amino acid dianion). The latter was found to prevail at high pH values, where N-dansylglycine, in addition, forms the mixed hydroxo species [Pd(LNO)(OH)]^–. These complexes are more stable than the corresponding ones formed by Cu^II and Cd^II. Palladium(II) is more effective than Cu^II and Cd^II in promoting amide-nitrogen deprotonation in this class of ligands, as previously observed with peptides.