Why does Carbon Monoxide bind with Haemoglobin 200 times more than Oxygen?

Question

Why does Carbon Monoxide bind with Haemoglobin 200 times more than Oxygen?

Answer 1

Ubczoo has got it muddled. CO has empty pi-ANTIbonding orbitals, localised mainly on the carbon, so that it is an example of a pi-accepting ligand.  It accepts electron density from the iron full dxz and dyz orbitals (if we label the axis that CO is on, z).

Experimental evidence: the fact that CO binds specifically to metals in low oxidation states, and that this is accompanied by a reduction in CO stretching frequency.

Answer 2

since you guys are correct..what more can i say

Answer 3

Paul is correct and actually O2 exists as a diradical in its ground state .

Answer 4

CO as a compound has extra electrons in the P shell to form bonds with Heme. On one hand you have a donor of electrons and on the other hand you have a very strong acceptor of electrons. Perfect combo.

Oxygen is diatomic and it is very happy and stable in its bonds together w/ another Oxygen atom and does not wish to break up to join heme.

hence the difference in bond affnity.