Copper complexes of 3-phenyl-hydrazo acetylacetone and its ortho, meta and para carboxy derivatives have been prepared. These complexes have been studied using electron spin resonance, infra red and u.v. spectroscopic techniques. All these ligands form 2:1 (ligand: copper) complexes and in the case of the ortho derivative a 1:1 complex is also formed. The 3-phenyl-hydrazo acetylacetone forms a 2:1 complex in which the copper atom is co-ordinated with the hydrazo nitrogen and the C=O oxygen from each ligand. In the case of the ortho compound a 1:1 complex can also be formed. The co-ordination requirements of the copper being satisfied through the hydrazo nitrogen, one C=O oxygen, and the O-of the ortho-carboxy ion together with a solvent molecule. The 2:1 complex of the ortho compound (in which the co-ordination requirements of copper are satisfied by one hydrazo nitrogen and one C=O from each ligand) is not as stable as the 2:1 complex for the unsubstituted ligand because the ortho group introduces very large steric hinderance which results in this 2:1 complex being rapidly converted into the 1:1 complex. For the para complex there is no 1:1 complex because the carboxylic acid group is too far from the copper to co-ordinate with it. In the meta compound for the same reasons the stable complex is the 2:1 type. © 1979, Taylor & Francis Group, LLC. All rights reserved.
