Synthesis and characterization of nickel(II) and copper(II) complexes of hexaaza macrocycle, 4-methyl-1,3,5,8,11,14-hexaazatricyclooctadecane

The Ni(II) and Cu(II) complexes of a new 14-membered hexaazamacrocycle, 4-methyl-1,3,6,8,11,14-hexaazatricyclooctadecane (PCHA) in which a methyl group is attached to the macrocyclic frame work has been synthesized by the one pot reaction of triethylenetetraamine, formaldehyde and 1,2-propanediamine in the presence of metal ion. The complexes have been characterized by spectroscopic, electrochemical and molar conductivity measurements. The Ni(II) complex exists in solution as a mixture of octahedral, high-spin and planar, low-spin species; the thermodynamic parameters for the spin interconversion depend on the cyclic nature of the ligand. The crystal structure of [Ni(PCHA)](ClO4)2 was determined by X-ray crystallography.

Square-planar Ni(II) and Cu(II) complexes of macrotricyclic ligand 4-methyl-1,3,6,8,11,14-hexaazatricyclooctadecane (PCHA) have been synthesized from the template condensation reactions of formaldehyde with triethylenetetraamine and 1,2-propanediamine in the presence of metal ion. The complexes have been characterized by spectroscopic, electrochemical and molar conductivity measurements. The crystal structure of [Ni(PCHA)](ClO4)2 determined by X-ray crystallography confirms a square-planar geometry around the metal centre.Figure optionsDownload as PowerPoint slide