The coordination chemistry of ethylenediaminetetraacetic acid EDTA involves its ability to form stable complexes with metal ions through a process called chelation. EDTA is a hexadentate ligand, meaning it can bind to a central metal ion through six coordination sites. The molecule has four carboxylate groups -COO- and two amine groups -NH2 that can donate electron pairs to form coordinate covalent bonds with metal ions.In chelation therapy, EDTA is used to remove heavy metal toxins from the body, such as lead, mercury, and cadmium. The mechanism of action involves the formation of stable, water-soluble complexes between EDTA and the heavy metal ions. The EDTA-metal complexes have a higher stability constant than the metal complexes with other ligands present in the body. This means that EDTA has a higher affinity for the heavy metal ions and can effectively compete with other ligands to form complexes with the metal ions.Once the EDTA-metal complexes are formed, they are less likely to dissociate and release the metal ions back into the body. This stability allows the complexes to be safely transported through the bloodstream and eventually excreted through the kidneys in the urine. By forming these stable complexes, EDTA effectively reduces the concentration of free heavy metal ions in the body, thereby decreasing their toxic effects and facilitating their removal from the body.