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 (1,2-ethylenediamine 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(NO 3 ) 2 ·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.