Design, synthesis and spectroscopic characterization of palladium(II) and platinum(II) complexes of pyrazole-derived ligands with potential anti-tumour properties in its historical perspective

Abstract

The synthesis and physico-chemical identification of a host of new palladium(II) and platinum(II) complexes with two strategically designed pyrazole-derived ligands, 3,5-dimethyl-1-(0-aminophenyl)pyrazole (DApPz) and 5-methyl-3-(2′-benzimidazolyl) pyrazole (MBP), are described. All the reported non-electrolytic monochelates, M(DApPz)X 2 and M(MBP)X 2 (M = Pd II or Pt II, X = a counterion) are planar species, as ascertained from electronic spectral features together with the LF parameters. The proven (NN) bidentate nature of the pyrazole-based primary ligand(s) along with relevant IR data classify the complexes as cis derivatives. 1H NMR data of the uncomplexed ligand(s) and of the reported diamagnetic Pd II and Pt II species (recorded in DMSO- d 6 at 300 MHz) are commensurate with the conclusions (drawn from IR spectral features) that primary ligand DApPz is bonded to Pd II or Pt II through the pyrazolyl (ring) nitrogen and the amino nitrogen, and that MBP functions through N(2) of the pyrazole and N(3) of the imidazole moieties in complexation.