Studies on the interaction of iron(II), nickel(II), copper(II) and zinc(II) with tetraazamacrocycles

Abstract

The condensation of aliphatic diamines H₂N(CH₂)_nNH₂ (n = 2-3) with dicarboxylic acid HOOC - (CH₂)_n- COOH (n = 1-2) in the presence of dicyclohexyl-carbodiimide and 4-(dimethylamino) pyridine results in new types of 14-18 membered tetraamide macrocyclic ligands <b>1a-1d.</b>. These compounds on reduction with LiAlH₄ yield a series of tetraazamacrocycles <b>2a-2d</b> which form complexes with Fe(II), Ni(Il), Cu(II) and Zn(II). The ligands and their complexes have been characterized by elemental analyses, mass, lR, ¹H NMR, UV/Vis, EPR spectroscopic, molar conductance and magnetic moment data. An octahedral geometry around the metal ion is suggested for [M2aCl₂][M2dCI₂], where M = Fe(II) and Ni(II) while a square-planar and a tetrahedral geometry is proposed for [M2a)CI₂^- [M2d)Cl₂ for M =Cu(II) and Zn(II).