Synthesis and crystal structure of some new cadmium (II) macrocyclic Schiff-base complexes containing piperazine moiety

The metal templated Cd(II) cyclocondensation of 2,6-diacetylpiridine or 2,6-pyridinedicarbaldehyde and two different amines containing piperazine moieties have been investigated. The resulting ligands, L1 and L2 are 16- and L3 and L4 17-membered pentaaza macrocycles. The complexes have been characterized by a variety of methods including IR, 1H, 13C NMR, DEPT, COSY(H,H), HMQC(H,C), FAB spectrometry and conductivimetry measurements. The crystal structures of [CdL2Cl](CH3OH)ClO4 (2) and [CdL4(NO3)(H2O)]ClO4 (4) have been also determined, and it was shown that the geometry of the Cd(II) ion in the complexes is slightly distorted pentagonal pyramidal and pentagonal bipyramidal, respectively. The gas-phase structures of ligands, L2 and L4 and their Cd(II) complexes have also theoretically studied.

Graphical abstractThe Cd(II) metal templated cyclocondensation of four new pentaaza macrocyclic ligands starting from 2,6-diacetylpyridine or 2,6-pyridinedicarbaldehyde with two different tetra-amines containing piperazine moiety have been successfully achieved. The complexes have been characterized by a variety of methods including IR, 1H, 13C NMR, DEPT, COSY(H,H), HMQC(H,C), FAB spectrometry and conductivimetry measurements. The crystal structures of [CdL2Cl(CH3OH)]ClO4 and [CdL4(NO3)(H2O)]ClO4 have been also determined.Figure optionsDownload full-size imageDownload as PowerPoint slide