Chapter 4, Problem 123CP

Carbon monoxide (CO) forms bonds to a variety of metals and metal ions. liS ability to bond to iron in hemoglobin is the reason that CO is so toxic. The bond carbon monoxide forms to metals is through the carbon atom:

$M—C\equiv O$

a. On the basis of electronegativities, would you expect the carbon atom or the oxgen atom to form bonds to metals?

b. Assign formal charges to the atoms in CO. Which atom would you expect to bond to a metal on this basis?

c. In the MO model, bonding MOs place more electron density near the more electronegative atom. (See the HF molecule in Figs. 4-54 and 4-55.) Antibonding MOs place more electron density near the less electronegative atom in the diatomic molecule. Use the MO model to predict which atom of carbon monoxide should form bonds to metals.