In recent years the importance of metal ions for smooth operation of plant and animal organisms were evidenced by the publication of numerous papers in the field of biophysics and biochemistry. Latest researches in these areas focus on the synthesis and characterization of biological compounds containing metal ions, due to their applicability in pharmacy, medicine, agronomy and nutrition. Three Transition metal complexes of iron were synthesized by the Amino acids using Cysteine in presence of co-ligand NaN3 using different metal, ligand and co-ligand ratio. Amino acids usually acts as bidentate ligand, coordinate with Nitrogen atom of Amino group (NH2) and oxygen atom of Carbonyl group (CO), but in case of cysteine there are chances of Sulphur incorporation with metal. These complexes were characterized by means of electronic spectroscopy, Infrared spectroscopy, Powder X-rays diffractometer.