Synthesis, spectroscopic, DFT, cytotoxicity and antimicrobial activity of Pd(II) and Pt(II) complexes of N,N-chelated benzimidazole derivatives

New cis-platin analogs Pd^II and Pt^II complexes of (1H-benzimidazol-2-ylmethyl)-N-(4-chloro-phenyl)-amine (L^Cl) and (1H-benzimidazol-2-ylmethyl)-N-(4-iodo-phenyl)-amine (L^I) were prepared as potential antitumor compounds, characterized (elemental analysis, TG/DTA, FT IR, ¹H NMR, MS, UV-Vis. and conductance measurements) and tested for their cytotoxic activities against MCF7, HCT and HEPG2. The antibacterial activity was tested on against Staphylococcus aureus, Bacillus subtilis, Streptococcus faecalis, Escherichia coli, Pseudomonas aeruginosa and Neisseria gonorrhea. The effect of the aniline substituent on the toxicity was discussed. The experimental studies were complemented by quantum chemical calculations. TD-DFT calculations were carried out to understand the electronic structure and to explain the related experimental findings. Natural bond orbital analysis was performed to provide details about the electronic arrangement, type of hybridization and the nature of bonding.