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...