Synthesis, Structure, and Biological Activity of Binuclear Mixed-Ligand Complexes of Nickel(II) Benzoylhydrazone 2-(N-Tosylamino)Benzaldehyde

Two new complexes of nickel(II) benzoylhydrazone 2-(N-tosylamino)benzaldehyde (H₂L) with additional heterocyclic donor ligands L¹ = 2,2′-bipyridine and L² = 1,10-phenanthroline are synthesized. Structures and compositions of the obtained compounds are determined by elemental analysis, ¹H NMR, and IR techniques. Crystal and molecular structures of the Ni(II) complexes are determined by single crystal X-ray diffraction. The adducts are shown to have dimeric structures: Ni₂L₂L¹(CH₃OH) and Ni₂L₂L²(CH₃OH). In both adducts, one of nickel(II) ions is in a distorted square-planar environment while another is in the octahedral environment due to additional coordination of 2,2′-bipyridine or 1,10-phenanthroline and a methanol molecule. The biological activity of the complexes is studied. It is found that both adducts exhibit the protistocidal activity against Colpoda steinii, with Ni₂L₂L¹(CH₃OH) being twice less active and Ni₂L₂L²(CH₃OH) being twice more active than the chloroquine reference.