Magnetic susceptibility of Tri-Coordinated copper(II) complexes

The magnetic susceptibilities of salicylal-o-hydroxybenzylamine Cu(II), salicylal-o-hydroxyanil Cu(II), acetylacetone-mono-(0-hydroxyanil) Cu(II), and benzoylacetone- mono-(0-hydroxyanil) Cu(II), as well as their pyridinates, have been measured by the Gouy method at room temperature. The effective magnetic moments calculated from the . data of the pyridine-free complexes per one copper atom are smaller than the theoretical moment, 1.73 B.M., for one odd electron. Although it has been presumed from the method of synthesis, the chemical analysis of the complexes, and the tridentate nature of the ligand molecules that the copper atoms of the chelates have the unusual coordination number 3, the subnormal magnetic moments suggest the presence of dimeric molecules, in which two copper atoms are very close to each other as in cupric acetate monohydrate. On the other hand, the pyridinates have normal magnetic moments expected for tetra-coordinated copper complexes.