Synthesis, structures, and antimicrobial activities of two cobalt(II) complexes [Co(L1)2(OH2)2] and [Co(L2)2]

Abstract

A new cobalt(II) complex, [Co(L¹)₂(OH₂)₂] (1), was prepared by the reaction of 3-bromo-5-chlorosalicylaldehyde (HL¹) with cobalt nitrate in methanol. Reaction of 1 with cyclopropylamine in methanol afforded the Schiff base cobalt(II) complex, [Co(L²)₂] (2), where L² is the deprotonated form of 2-bromo-4-chloro-6-(cyclopropyliminomethyl)phenol (HL²). The complexes have been characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction. The L¹ ligand coordinates to the Co atom through the phenolate O and carbonyl O atoms, while the L² ligand coordinates to the Co atom through the phenolate O and imino N atoms. The Co atom in complex 1 adopts octahedral coordination and that in complex 2 adopts tetrahedral coordination. The effect of the free ligands and the cobalt complexes on the antimicrobial activities against Staphylococcus aureus, Escherichia coli, and Candida albicans was studied.