Cobalt(II) complexes based on (1-methyl-1H-benzo[d]imidazol-2-yl) methanol derivative: synthesis, crystal structure, spectroscopy, DFT calculations, and antioxidant activity

In this paper, we present a combined experimental and computational study of two new cobalt(II) complexes as [Co(Hmbm)2(OAc)2] and [Co(Hmbm)2(H2O)2]Cl2 (Hmbm = (1-methyl-1H-benzo[d]imidazol-2-yl)methanol). Both complexes were characterized by FT-IR and UV–vis spectroscopy, elemental analysis, and single-crystal X-ray crystallography. The molecular geometries, electronic transitions, and vibrational frequencies of the two complexes and the ligand (Hmbm) in the ground state have been calculated using global hybrid (B3LYP) and range-separated hybrid (CAM-B3LYP) density functional. Qualitative description of excited states and charge transfer character of electronic transitions states were carried out by plotting the Natural Transition Orbitals (NTOs) for main states, and were assigned to LMCT. The ligand and its Co(II) complexes have been evaluated for their potential as DPPH radical scavengers.