Structural, magnetic and theoretical study of mononuclear nickel(II) and cobalt(II) compounds of a benzimidazole thiobutanoic acid derivative

•Antiferromagnetic coupling in mononuclear cobalt(II) and nickel(II) compounds.•DFT calculations showed magnetic pathways through non-covalent interactions.•Octahedral coordination compounds of 4-(benzimidazol-2-yl)-3-thiabutanoic acid.•Tridentate ligand with N, S and O coordination sites.

A structural, magnetic and theoretical study of the mononuclear octahedral cobalt(II) and nickel(II) coordination compounds with the tridentate ligand, 4-(benzimidazol-2-yl)-3-thiabutanoic acid (Hbztb), was performed. At low temperature, both compounds present weak antiferromagnetic couplings via intermolecular interactions. In the [Co(bztb)2]·H2O compound, intermolecular hydrogen bonding between the benzimidazolic nitrogen atom and the neighboring carboxylic oxygen contribute to the magnetic pathway for the coupling between the cobalt(II) mononuclear complexes. Whereas in [Ni(bztb)2]·3H2O, two nickel(II) compounds are linked by non-covalent interactions through water molecules, [(Ni(bztb)2⋯(H2O)3⋯Ni(bztb)2], which play an important role on the super-exchange magnetic coupling contributing to the magnetic MO. The magnetic behavior of both coordination compounds was analyzed by DFT theoretical calculations.

Graphical abstractA structural, magnetic and theoretical study of two mononuclear cobalt(II) and nickel(II) coordination compounds, with the tridentate NSO ligand, 4-(benzimidazol-2-yl)-3-thiabutanoic acid (Hbzta), was carried out. Both compounds presented weak antiferromagnetic couplings. This magnetic behavior is due to non-covalent interactions: in the Co2+ complex, hydrogen bonding between two mononuclear compounds; and in the case of the Ni2+ compound, three intermolecular water molecules are participating in the magnetic MO. The magnetic behavior of both complexes was analyzed by DFT theoretical calculations.Figure optionsDownload full-size imageDownload as PowerPoint slide