Chelating Behavior of 14‐Membered Schiff Base Macrocycles and Their Transition Metal Chelates

Abstract

The new Schiff base 14‐membered macrocycles, 1,5,8,12‐tetraazacyclotetradeca‐6,7,13,14‐tetraaminoacetic acid‐5,7,12,14‐tetraene (L¹), 1,5,8,12‐tetraazacyclotetradeca‐6,7,13,14‐tetraaminophenyl‐5,7,12,14‐tetraene (L²) and 1,5,8,12‐tetraazacyclotetradeca‐6,7,13,14‐tetraaminopyridyl‐5,7,12,14‐tetraene (L³), have been synthesized by the reaction of N,N‐dicarboxymethyloxamide, N,N‐diphenyloxamide or N,N‐dipyridyloxamide with 1,3‐diaminopropane. Their complexes with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) ions have been prepared and characterized by elemental analyses, IR, ¹H NMR and electronic spectra, magnetic moment and conductivity measurements. The complexes of the divalent metal ions are non‐ionic while those of the trivalent metal ions appear to be 1:1 electrolytes. On the basis of these studies an octahedral geometry is proposed for all of the complexes.

Keywords:

• 14‐Membered macrocycles
• Schiff base
• Synthesis
• Metal chelates