Synthesis and characterization of hetero-bimetallic complexes with 2-mercapto-5-methyl-benzimidazole: theoretical study and biological activities

Heterobimetallic complexes have been synthesized by stirring 2-mercapto-5-methylbenzimidazole with carbon disulfide in methanol at room temperature. In the second step, the product was treated with R2SnCl2/R3SnCl (R = Me, n-Bu, Ph) in 1 : 1 M ratio, then organotin(IV) complexes were treated with HgCl2 in 2 : 1 M : L ratio to yield heterobimetallic complexes. The ligand and complexes have been characterized by elemental analysis, IR, 1H- and 13C NMR spectroscopy, mass spectrometry (EI-MS), and semiempirical study to assess the binding mode of the heterobimetallic complexes. IR data showed the bidentate nature of the dithiocarbamate moiety, which is also confirmed by semiempirical study. Mass spectra correspond to the expected for the complexes. NMR spectroscopy confirmed the four-coordinate geometry in solution. Computed molecular descriptors, thermodynamic parameters, and electrostatic surface potential map of 4 were calculated by using the PM6 method. Biological screening data indicated that complexes exhibit significant activity against various bacterial and fungal strains with few exceptions. Ligand and 6 are excellent for phagocyte reactive oxygen species inhibition.