Mn(II) and Cd(II) macrocyclic Schiff base complexes with a single pendant coordinating 2-pyridylmethyl arm: Synthesis, X-ray crystal structure and NMR studies

The cyclocondensation reaction of N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,2-diaminoethane, L22py, with both 2-[2-(2-formyl phenoxy)ethoxy] benzaldehyde and 2-[3-(2-formyl phenoxy)propoxy]benzaldehyde, and reaction of N-(2-pyridylmethyl)-N-(2-aminoethyl)-1,3-diaminopropane, L33py, with 2-[2-(2-formyl phenoxy)ethoxy] benzaldehyde in the presence of equimolar amounts of Cd(II) or Mn(II) metal ions is reported. The resulting compounds [CdL1Cl](ClO4)·1/2CH3CN (1), [MnL1Cl](ClO4) (2), [CdL2(NO3)](ClO4)·CH3CN (3), [MnL2Cl]ClO4 (4), [CdL3Cl](ClO4)·H2O (5) and [MnL3Cl]ClO4 (6) were characterized by IR spectroscopy, elemental analysis and mass spectrometry in all cases and by X-ray and NMR in the case of the Cd(II) complexes. X-ray single crystal structure analysis of a selected single crystal of compound (1) showed that it contains two cations (A) and (B), [CdL1Cl]+, with similar N4OCl donor sets. In contrast, the results of microanalysis, NMR and mass spectra showed that in the bulk sample, there are two different cations [CdL1Cl]+ and [CdL1(NO3)]+ in the ratio of 4–1, respectively. X-ray crystal structure determination of other cadmium complexes, (3) and (5), confirmed that in addition to the expected macrocylic ligand with a N4O2 donor set, the NO3- and Cl− anions are coordinated to the central metal ion, respectively.

Six new macrocyclic Schiff base complexes were prepared by the template condensation of two tripodal ligands and with 2-[2-(2-formyl phenoxy)ethoxy] benzaldehyde and 2-[3-(2-formyl phenoxy)propoxy]benzaldehyde in the presence of Cd(NO3)·4H2O or MnCl2 in equimolar ratios. The resulting compounds were characterized by IR spectroscopy, elemental analysis and mass spectrometry in all cases and by X-ray and NMR in the case of all Cd(II) complexes.Figure optionsDownload as PowerPoint slide