Manganese has variable oxidation states and appears as Mn(III) with redox function. It plays an important role in numerous biological processes associated with utilization or generation of hydrogen peroxide or dioxygen. The functions of these type are known viz manganese superoxide dismutase, manganese catalase , manganese peroxidase, manganese ribonucleotide reductase and oxygen involving complex in photo system-II. This has prompted to under take the coordination of Mn(III) ions with ligands. The oxygen donar ligands used for the coordination are ?-diketones since ?-diketones anions are powerful chelating species and they give stable Mn(III) complex which can further be used for preparing other Mn(III) species that can be used as catalysts. The tris (?-diketonate) Mn(III) complex gives substitution as well as addition reactions with other ligands. Here nitrogen donar ligands used are ethylenediamine. The nitrogen donar atom ligands ultimately result in the mixed ligand complexes for Mn(III) which are more stable in this oxidation state of manganese. In this way the aim of preparing stable Mn(III) complexes is achieved by the oxygen donor atom and nitrogen donor atom ligands.