Synthesis,Characterization, and Screening for Antiamoebic Activity of Palladium(II), Platinum(II), and Ruthenium(II) Complexes with NS‐Donor Ligands

Reaction of PdCl₂(DMSO)₂], PtCl₂(DMSO)₂], and RuCl₂(η⁴‐C₈H₁₂)(MeCN)₂] with S‐acetyl N^β‐acetyldithiocarbazate (=2‐acetylhydrazinecarbodithioic acid anhydrosulfide with ethanethioic acid; aadt; 1 ), S‐methyl N^β‐(5‐nitrothiophene‐2‐yl)methylene]dithiocarbazate (=S‐methyl 2‐(5‐nitrothiophene‐2‐yl)methylene]hydrazinecarbodithioate; mntdt; 2 ), and S‐benzyl N^β‐(5‐nitrothiophene‐2‐yl)methylene]dithiocarbazate (=S‐benzyl 2‐(5‐nitrothiophene‐2‐yl)methylene]hydrazinecarbodithioate; bntdt; 3 ) led to new complexes PdCl₂(L)], PtCl₂(L)], and RuCl₂(η⁴‐C₈H₁₂)(L)] (L=ligands 1 – 3 ). All these compounds were characterized by elemental analysis, IR, ¹H‐ and ¹³C‐NMR and UV/VIS spectra and thermogravimetric analysis. Ligand 1 coordinates through the thioxo S‐atom and the carbazate N(β) atom, whereas in ligands 2 and 3 the thioxo S‐atom and the azomethine N‐atom are coordinated to the metal ion. Screening of antiamoebic activity of these compounds was performed in vitro against the HK‐9 strain of E. histolytica. All the complexes were more active than their respective ligands; compound 3a showed the most promising activity.