N,N’-Bis(4-Bromo-2-hydroxybenzylidene)ethylenediamine and Its Copper(II), Zinc(II) and Cobalt(III) Complexes: Synthesis, Crystal Structures and Urease Inhibition

Abstract

A new Schiff base compound N,N’-bis(4-bromo-2-hydroxybenzylidene)ethylenediamine (H₂L) was prepared by reaction of 4-bromosalicylaldehyde with ethane-1,2-diamine in methanol. Reaction of H₂L with copper acetate and zinc acetate in methanol, respectively, afforded two mononuclear complexes [CuL] (1) and [ZnL(OH₂)] (2). Reaction of H₂L with cobalt nitrate in the presence of ammonium thiocyanate in a mixture of methanol and DMF afforded a mononuclear cobalt(III) complex [CoL(NCS)(OH₂)]·DMF (3). The free Schiff base and the complexes were characterized by elemental analysis and infrared spectra, as well as single crystal X-ray determination. ¹H NMR spectrum was also performed for H₂L. The deprotonated form of the Schiff base coordinates to the metal atoms through all the phenolate oxygen and imino nitrogen atoms. The Cu(II) atom in complex 1 is in square planar coordination. The Zn(II) atom in complex 2 is in square pyramidal coordination. The Co(III) atom in complex 3 is in octahedral coordination. The urease inhibitory assay reveals that the copper(II) complex has the most effective activity.