Haemoglobin is an oxygen carrying protein. The correct statement about...
Explanation:
Haemoglobin molecule contains a heme group which is composed of iron (Fe) atom in the center of a porphyrin ring. The iron atom in heme group can exist in different oxidation states, including +2 (ferrous) and +3 (ferric).
When oxygen binds to the iron in the heme group, it forms oxy-haemoglobin. The oxygen molecule (O2) binds to the iron in a reversible manner and forms an iron-oxygen complex.
The correct statement about oxy-haemoglobin is that the metal is low-spin in 3 oxidation state while dioxygen is in O2-. This means that when oxygen binds to the iron in oxy-haemoglobin, the iron is in a low-spin state with a 3+ oxidation state, while the oxygen molecule is in a negatively charged O2- state.
The reason for this is due to the nature of the bonding between the iron and oxygen atoms. The iron atom in the heme group has six coordination sites, which can be occupied by various ligands. In the case of oxy-haemoglobin, the oxygen molecule binds to the iron atom through two of these coordination sites, forming a covalent bond.
The nature of the bonding between the iron and oxygen atoms is such that the iron atom is in a low-spin state with a 3+ oxidation state, while the oxygen molecule is in a negatively charged O2- state. This is because the iron atom has a strong affinity for electrons, which causes the oxygen molecule to transfer its electrons to the iron atom, resulting in the formation of the negatively charged O2- ion.
In summary, the correct statement about oxy-haemoglobin is that the metal is low-spin in 3 oxidation state while dioxygen is in O2-.