New mononuclear lanthanide(III) macrocyclic polymeric complexes with the 1,5,9,13-tetraazacyclohexadecane ligand: Their magnetic studies and semiempirical calculations

Novel mononuclear lanthanide polymeric complexes are formed with Nd(III), E u(III), Gd(III), Tb(III), Er(III) and Lu(III) nitrates and the 1,5,9,13-tet raazacyclohexadecane ligand. These compounds were characterized by elementa l and thermal analysis, IR, EPR, H-1 and C-13 NMR spectroscopies and magnet ic susceptibility at variable temperature. The molecular weight of the comp ounds was determined by gel permeation chromatography, the results of which are 6272, 6120 and 4121g/mol for Nd(III), Gd(III) and Er(III) compounds, r espectively. The structures for the monomeric unit and the polymers were ca lculated by the force-field method. Each lanthanide compound showed specifi c and unusual magnetic properties which were associated with the particular arrangement of the elemental units in each polymer.