Palladium(II) complexes of N-sulfonylamino acids. Part 2. Co-ordination behaviour under strongly acidic conditions

Abstract

The ligation of a series of N-sulfonylamino acids (H₂L) to Pd²⁺ was investigated by means of d.c. polarography, ¹H NMR and electronic spectroscopy. The first amino acid is found to bind to the metal under extremely acidic conditions, with an apparent pK_NH value of about 1, while an additional molecule binds with a pK_NH ranging from 3.1 to 3.7 for the different amino acids. These nitrogen-deprotonated complexes appear not to involve carboxylate complexes as stable precursors. Proton NMR spectroscopy indicates the presence of geometric isomers for the [PdL₂]^2– species.