The coordination of dioxygen in haemoglobin features an active site that is represented by the sketch shown. Start with basic principles of bonding and use suitable diagrams to explain the

special properties of haemoglobin, including (a) Perutz's trigger, (b) End-on angular coordination, (c) Differences in oxidation state, coordination number,coordination geometry, ionic radii, and magnetic spin that may occur between the deoxygenated and oxygenated forms, (d) Why do mammals not rust from the inside out? (e) A description of the different types of bonds that Fe forms with amino a the various ligands, and(4 marks) (f) How do you expect the active site to bond with a CN` ion?