Synthesis and spectroscopic characterization of new chiral ONS Schiff base ligands and their asymmetric Pd(II) complexes

Two new chiral tridentate-ONS Schiff bases (S)-HL1 and (S)-HL2 were synthesized by the condensation of (2S)-1-phenyl-3-(phenylsulfanyl)propan-2-amine (1d) with 3-methoxy-2-hydroxybenzaldehyde and 3,5-di-tert-butyl-2-hydroxybenzaldehyde respectively. The corresponding asymmetric palladium(II) complexes [PdCl((S)-L1)] (1) and [PdCl((S)-L2)] (2) were synthesized by the reaction of (S)-HL1 and (S)-HL2 with sodium tetrachloropalladate in water. The structures and compositions of the newly synthesized ligands and complexes were confirmed by FT-IR,1H/13C{1H} NMR, UV-visible spectroscopy, and elemental analysis. According to the characterization data, both the ligands (S)-HL1 and (S)-HL2 were coordinated to the core Pd(II) ion as monobasic [(S)-L1 and (S)-L2] tridentate (O, S, N) chelates in the respective complexes.