Three platinum(II) coumarin derivative-dppf complexes: Stoichiometry and pH-dependent formation with single-crystal, anticancer, and computational studies

Three novel platinum (II) mixed-ligand complexes were yielded by reacting a coumarin derivative (CoumH) and 1,1'-bis(diphenylphosphino)ferrocene (Dppf) with Pt(II)salt. This reaction was carried out by using a two-step method in neutral and basic media. To identify the resulting complexes, various spectroscopic techniques were used, including single-crystal diffraction, FTIR, UV-Vis, NMR spectroscopy, and CHN analysis. The NMR data of the complexes prove that the coumarin derivative behaves differently depending on the medium, whether it is basic or neutral; in neutral conditions, the coumarin derivative coordinates as a monodentate ligand through its keto oxygen. In basic media, the deprotonated ligand forms a bidentate coordination with the oxygen atom and anionic oxygen. All Pt(II) complexes show square planar geometry and have the following chemical formula: [Pt(Dppf)Cl₂]. H₂O (1), [Pt(CoumH)₂(Dppf)]Cl₂ (2), and [Pt(Coum)(Dppf)]Cl (3). Pt(II) complexes were evaluated against two types of bacteria, Escherichia coli and Staphylococcus aureus. [Pt(Coum)(Dppf)]Cl complex exhibited excellent antibacterial activity against both bacteria. Additionally, the cytotoxicity results revealed that complexes [Pt(CoumH)₂(Dppf)]Cl₂, and [Pt(Coum)(Dppf)]Cl have potential antitumor activity and inhibited 69% and 63% of cancer cells, respectively. Stability and molecular reactivity of the complexes have been established through the utilization of density functional theory (DFT), Hirshfeld surface, and non-covalent interaction analysis. KEY WORDS: Platinum(II) Complexes, Coumarin derivatives, Dppf ligand, Anticancer, DFT study Bull. Chem. Soc. Ethiop. 2026, 40(4), 907-927. DOI: https://dx.doi.org/10.4314/bcse.v40i4.13