Synthesis, crystal structure and spectroscopic properties of some cadmium(II) complexes with three polyamine and corresponding macroacyclic Schiff base ligands

Three Cd(II) macroacyclic Schiff base complexes [CdL4(NO3)2] (4), [CdL5(NO3)2] (5), [CdL6(NO3)2] (6) were prepared by template condensation of 2-pyridinecarboxaldehyde with N1-(2-nitrobenzyl)-N1-(2-aminoethyl)ethane-1,2-diamine (L1), N1-(2-nitrobenzyl)-N1-(2-aminoethyl)propane-1,3-diamine (L2) or N1-(2-nitrobenzyl)-N1-(3-aminopropyl)propane-1,3-diamine (L3), in the presence of cadmium metal ion, respectively. Three Cd(II) complexes with L1, L2 and L3 were also synthesized. All complexes have been studied with IR, 1H NMR, 13C NMR, DEPT, COSY, HMQC and microanalysis. Two of these complexes, [CdL4(NO3)2] (4) and [CdL1(NO3)2] (1) have been characterized through X-ray crystallography. In complex 4, the Cd is in a six-coordinate environment comprised of the ligand N4-donor set and two oxygen atoms of two nitrate groups. In the polyamine complexes (1, 2 and 3) Cd and ligand are in a ratio of 1:1. Supporting ab initio HF–MO calculations have been undertaken using the standard 3-21G∗ and 6-31G∗ basis sets.