Synthesis, solution behaviour and potential anticancer activity of new trinuclear organometallic palladium(II) complex of S-1-phenylethyl dithiooxamide: Comparison with the trinuclear heterobimetallic platinum(II) analogue

Addition of H2R2DTO (R={S}-1-phenylethyl and DTO= dithiooxamide) to the bis(benzonitrile)palladium(II) chloride complex in chloroform afforded the mononuclear Pd(DTO)2.2HCl complex. The complex treated with NaHCO3 for removing of HCl and then reacted with [Pd(ƞ3-allyl)(µ-Cl)]2 for preparation of a new trimetallic organopalladium(II) complex. The molecular structure of the trimetallic complex was determined by X-ray diffraction indicating a planar geometry around each palladium centre. The structure of the trinuclear Pd(II) complex with details was computed by DFT calculations. Also, variable temperature spectroscopy for this complex was performed in CDCl3 in the range 298-390 K, and simulations of the dynamic spectra were performed using the gNMR program. A comparison between the target-based activity of the Pd(II) complex and its trinuclear heterobimetallic platinum(II) analogue as potential anticancer agents was also conducted. All the biological tests showed that both Pd(II) and Pt(II) complexes can fairly inhibit cathepsin B (Cat-B) and cathepsin L (Cat-L) as well as two out of three activities of 20S proteasome.