Preparing Mn(III) salen-type Schiff base complexes using 1,3-oxazines obtained by Mannich condensation: towards removing ortho-hydroxyaldehydes

In this research a new method for preparing Mn(III)-salen complexes from 1,3-oxazine compounds has been investigated. The ligands were synthesized from the Mannich condensation of 1,2-diamines (1,2ethylenediamine or 1,2-cyclohexanediamine) with phenolic compounds (2-naphthol or 4-flourophenol) and formaldehyde solution under reflux conditions. The reaction of the ligands with Mn(NO3)(2)center dot 4H(2)O in methanol gave Mn(III) Schiff base complexes. The obtained compounds were characterized by elemental analysis and spectroscopic methods. The crystal structures of the ligand and complexes were characterized by single crystal X-ray diffraction studies. These analyses show that Mn(III)-salen type Schiff base complexes can be synthesized from the Mannich condensation of diamines, formaldehyde and phenols. This method eliminates the restrictions on the use of ortho-hydroxyaldehydes in preparing Mn(III)-Schiff base complexes.