SYNTHESIS AND CHARACTERIZATION OF MANGANESE(III) UNSYMMETRICAL SCHIFF-BASE COMPLEXES - A UNIQUE EXAMPLE OF A COCRYSTALLISED MANGANESE(III) UNSYMMETRICAL SCHIFF-BASE COMPLEX, AND A SYMMETRICAL SCHIFF-BASE COMPLEX ARISING FROM REARRANGEMENT OF THE FORMER

Some manganese(III) complexes with unsymmetrical Schiff bases have bee n prepared and characterised. The ligands were prepared by condensatio n of 7-amino-4-methyl-5-azahept-3-en-2-one with salicylaldehyde, 2-hyd roxyacetophenone or substituted salicylaldehydes (5-chloro, 5-methoxy, 3-ethoxy or 3,5-dibromo). On reaction with manganese(II) perchlorate in air, manganese(III) Schiff-base complexes are obtained. The crystal structures of two of these have been determined, one being cocrystall ised with [{Mn(salen)(H2O)}2][ClO4]2 containing the symmetrical salen ligand [N,N'-ethane-1,2-diylbis(salicylideneiminate)]. Unlike the dime ric structures previously found for similar complexes, the two structu res are monomeric with octahedral MnN2O4 co-ordination spheres.