Synthesis and spectroscopic studies of platinum (II) and palladium (II) complexes with amino acids and polypyridyl ligands

Abstract

Ten amino acid complexes of platinum (II) and palladium (II) of the type [M(L−L)(a−a)]Cl (where M=Pt or Pd; L−L=bidentate polypyridyl chelating agents and a−a=amino acids, S-methyl-L-cysteine or L-methionine) have been synthesized and characterized by various physical methods. The conductivity data show that these complexes are 1∶1 electrolytes and confirm the above formation. The ultraviolet spectra of these complexes show π-π* bands of polypyridyl ligands and MLCT bands, whiled−d bands are obscured. The1H NMR spectra of these complexes show that the amino acids are bonded to platinum and palladium through nitrogen and sulphur atoms. The infrared data have further supported the above bidentate mode of binding of the amino acids while the carboxylate group of the amino acids remains uncoordinated and deprotonated in these complexes. The S-methyl-L-cysteine complexes exist as diastereoisomers due to the presence of a chiral sulphur atom as identified by1H NMR.