A new synthetic route for the preparation of a new series of 14–22-membered tetraoxomacrocyclic tetraamines and their transition metal complexes

Abstract

The condensation of aliphatic diamines H 2N(CH 2) n NH 2 ( n = 2–3) with dicarboxylic acids in the presence of DCC (dicyclohexylcarbodiimide) and DMAP [4-(dimethylamino)pyridine] gave new types of 14–22-membered tetraamide macrocyclic ligands L 1L 10 which were characterized by element analysis and mass, IR and 1H NMR spectroscopic techniques. The complexes of these macrocyclic moieties with some transition metal ions have also been synthesized. The mode of bonding and overall geometry of these complexes has been inferred through UV-vis, IR, 1H NMR and ESR spectral techniques as well as molar conductance and magnetic moment data. An octahedral geometry around the metal ion is suggested for [ML 1Cl 2]-[ML 10Cl 2], where M = Mn II, Fe II and Co II, while a square planar, a distorted tetrahedral and a tetrahedral geometry is proposed for [ML 1]Cl 2-[ML 10]Cl 2 for M = Ni II, Cu II and Zn II, respectively. Bonding parameters have been derived from the ESR hyperfine structure of copper and cobalt complexes.