Ligand Substitution in Haemoglobin
- Haemoglobin is one of nature's complexes using a transition metal ion
- The haem molecule is a complex with iron(II) at its centre
- Oxygen atoms form a dative covalent bond with the Fe(II) which enables oxygen molecules to be transported around the body in the blood
The haem molecule with iron(II) at its centre
- Oxygen molecules are not very good ligands and bond weakly to the iron(II)
- The weak bonds allows them to break off easily and be transported into cells
- Carbon monoxide is toxic because it is a better ligand than oxygen and binds strongly and irreversibly to the iron(II) preventing oxygen from being carried to the cells
- If oxygen attached to the haemoglobin (oxyhaemoglobin) is replaced by carbon monoxide (carboxyhaemoglobin), a darker red colour is produced in the haem complex
- A sign of carbon monoxide poisoning
- The condition anaemia occurs when a person does not have enough haemoglobin in their blood due to a loss of blood or deficiency in iron
- Deficiency in iron can be restored by taking iron sulfate tables in the diet
