COPPER(II) COMPLEXES OF 1,2-DI(IMINO-4′-ANTIPYRINYL)ETHANE AND 4-N-(4′-ANTIPYRYLMETHYLIDENE)AMINOANTIPYRINE

Abstract

Copper(II) complexes of the Schiff bases 1,2-di(imino-4′-antipyrinyl)ethane (GA) and 4-N-(4′-antipyrylmethylidene)aminoantipyrine (AA) have been synthesized and characterized by elemental analyses, electrical conductance in non-aqueous solvents, infrared, electronic and EPR spectra as well as magnetic susceptibility measurements. The complexes have the general formulae [Cu(GA)]X₂ (where X = ClO₄ or NO₃), [Cu(GA)X₂] (where X = Cl or Br), [Cu(AA)₂]X₂ (where X = ClO₄, NO₃ or Cl) and [Cu(AA)Br]Br. GA acts as a neutral tetradentate ligand coordinating through both carbonyl oxygens and both azomethine nitrogens. In the perchlorate and nitrate complexes of GA, both anions remain ionic while in the corresponding halide complexes both anions are coordinated to the metal ion. AA acts as a neutral bidentate ligand coordinating through one of the carbonyl oxygens and the azomethine nitrogen in the perchlorate, nitrate and chloride complexes, while the coordination of AA occurs in a neutral tridentate fashion through both carbonyl oxygens and the azomethine nitrogen in the bromide complex. In the perchlorate, nitrate and chloride complexes of AA both anions remain ionic, while in the bromide complex, one of the bromides is coordinated to the metal ion. A square-planar geometry is assigned around the Cu(II) ion in all these complexes except the chloride and bromide complexes of GA, which are of distorted-octahedral geometry.

ACKNOWLEDGMENTS

We thank the Heads of the Regional Sophisticated Instrumentation Centre, Indian Institute of Technology, Chennai and Indian Institute of Technology, Mumbai, for some instrumental analyses. We also thank the Mahatma Gandhi University, Kerala, India, for the award of a Junior Research Fellowship to one of us (NTM).