Synthesis and structural characterization of metal complexes of an unsymmetric N3O tetradentate Schiff base ligand

Abstract

The nickel(II) and copper(II) complexes of the unsymmetrical N3O tetradentate Schiff base ligand, H2ambprsal, which is the 1:1:1 condensation product of 2-aminobenzaldehyde (amb), 1,3-diaminopropane (pr) and salicylaldehyde (sal), were prepared by the reaction of HsalprNH2 (HsalprNH2 is the 1:1 monocondensate of salicylaldehyde with 1,3-diaminopropane) with 2-aminobenzaldehyde, metal nitrate and triethylamine in methanol. Replacement of the nickel in Ni(ambprsal) with FeCl was accomplished by reaction of Ni(ambprsal) with dimethylglyoxime in benzene followed by reaction with iron(III) chloride. Structural investigation was carried out on the nickel(II) and copper(II) complexes. Both Ni(ambprsal) and Cu(ambprsal) are monomeric and approximately square planar. The six-membered ring containing the metal, the azomethine nitrogen atoms and the three carbins of the 1,3 diaminopropane bridge adopt the symmetrical boat conformation with the metal and the central carbon atoms occupying the bow and stern positions. The conformation of the ligand and the N3O donor set may both contribute to the high spin state of the iron atom in Fe(ambpral)Cl.