Dinuclear tetrapyridyl pendant-armed azamacrocyclic complexes of Co(II), Ni(II), Cu(II) and Cd(II)

The coordination capability of the new tetrapyridyl pendant-armed azamacrocyclic ligand L, towards Co(II), Ni(II), Cu(II) and Cd(II) ions was studied. The ligand and the complexes were characterized by microanalysis, LSI mass spectrometry, IR, UV–Vis and NMR spectroscopy, magnetic studies and conductivity measurements. Crystal structures of [Co2L(CH3CN)2](ClO4)4·2CH3CN and [Cd2L(NO3)2](NO3)2·2H2O complexes have been determined. The X-ray studies show the presence of dinuclear endomacrocyclic complexes with the metal ion in a similar distorted octahedral environment, coordinated by one pyridyl bridgehead group, two amine nitrogen atoms and two pyridyl pendant-arms. The sixth coordination position around the metal ion is completed by one acetonitrile molecule in [Co2L(CH3CN)2](ClO4)4·2CH3CN and by one monodentate nitrate anion in [Cd2L(NO3)2](NO3)2·2H2O. Different sort of intramolecular non-classical hydrogen bonds were found in the crystal lattice of both structures.