Pd(II) and Pt(II) Mixed Ligand Complexes Containing 2,5-Dimercapto-1,3,4-Thiadizole and 1,2-Bis(diphenylphosphino)ethane Ligands, Synthesis, Characterization, Crystal Structure, Anticancer and Computational Studies

One pot reaction of K₂MCl₄ with two equivalents of 2,5-dimercapto-1,3,4-thiadiazole (dmtzsH₂) and one equivalent of 1,2-bis(diphenylphosphino)ethane (dppe) in MeOH/CH₂Cl₂ mixed solvents resulted in the formation of [M(dmtzsH)₂(dppe)], M = Pd 1 or Pt 2 in 49 and 77% yield respectively. The same products were obtained in 54 and 80% yield on using two equivalents of KOH in EtOH/CH₂Cl₂ mixed solvents. The prepared complexes were characterized by elemental analysis, magnetic susceptibility, molar conductance, UV–Visible, FT-IR, ¹H, ³¹P-{¹H} nmr spectroscopy and 1 by X-ray crystallography. The crystal structure of 1 reveal that the two dmtzsH ligands function as monodentate binding to palladium through the exocyclic sulfur atom in a thiolate form, whereas dppe binds in a bidentate chelate fashion. The two complexes 1 and 2 were evaluated for their anti-cancer activity using in vitro methods against the MCF-7 cell line, a type of Breast cancer cell. The results indicated that both complexes exhibit a promising anticancer effect, IC₅₀ values of 55 µg/ml at a concentration of 500 µg/ml. The stability and molecular reactivity of the ligands and complexes have been demonstrated through the utilization of density functional theory (DFT) and Hirshfeld analysis.