Anchoring mercapto-triazoles on dicarbonyl backbone to assemble novel binucleating, acyclic SNONS compartmental ligands

Abstract

A series of homobinuclear Co^II, Ni^II, Cu^II &nbsp;and Zn^II complexes of the form [M₂(Cl)_xL](H₂O)_y] have been synthesized, where L is the deprotonated form of a new acyclic ligand resulting from the Schiff base condensation or one mol of 2,6-diformyl-<i>p</i>-cresol and two moles of triazoles (4-amino-3-methyl-1,2,4-triazole-5-thione; 3-methylsulphydryl-4-amino-5- mercapto -1,2,4-triazole and 3,5 dimercapto-4-amino-1,2,4-triazolel and characterized by spectral, magnetic, thermal and redox properties. Cryomagnetic investigations (79-296 K) reveal a strong antiferromagnetic spin-exchange between the copper (II) ions (J based on <i>H </i>= -2 <i>J </i>S₁, <i>S</i>₂<i>, </i>is 260 cm^-1). The copper complex (Cu^II-Cu^II) oxidizes at a relatively low potential (+0.55 V <i>vs</i> saturated calomel electrode) leading to the formation of the corresponding Cu^III-Cu^III complex. The EPR spectra of the copper complexes indicate an isotropic or axially elongated or exchange coupled local molecular environment around the metal ion. All compounds including the ligands are antimicrobially active.