Novel Ni(II) and Zn(II) complexes coordinated by 2-arylaminomethyl-1H-benzimidazole: molecular structures, spectral, DFT studies and evaluation of biological activity.

[NiL(1,2)Cl(2)(OH(2))(3)]·zH(2)O and [ZnL(1,2)(CH(3)CO(2))(2)] (L(1)=(1H-benzimidazol-2-ylmethyl)-N-phenyl amine, z=0 and L(2)=2-[(1H-Benzimidazol-2-ylmethyl)-amino]-benzoic acid methyl ester, z=1) complexes have been synthesized and characterized by a variety of physico-chemical techniques. The central Ni(II) ion is coordinated by only the pyridine-type nitrogen (N(py)) of benzimidazole ring, three water molecules and two chlorido ligands forming a distorted octahedral geometry. Five coordinated zinc complexes were obtained, where the coordination sphere of zinc ion is made up of secondary amino group (NH(sec)), N(py) and two acetate groups, one acts as a unidentate and the other as a bidentate. A theoretical DFT/UB3LYP method combined with LANL2DZ basis set shows that all the metal-ligand bonds are of the L→M type. Electronic structures have been calculated using TD-DFT method. The antibacterial activity of NiL(2) complexes decreases by the introduction of COOCH(3) group in the ortho-position of the aniline moiety.