[r12214001]

Q：Which atom of CO molecule will bond with Fe in hemoglobin? discuss in MO diagram and theory.

A : Because the antibonding molecular orbitals have more carbon character (carbon is less electronegative than oxygen), one would expect the bond to form through carbon.

please tell me. Why we have to consider the antibonding? Is the antibonding has something to do with bonding with the metal?