Nature of the Iron–Oxygen Bond in Oxyhæmoglobin

Abstract

THE essence of my suggestion was that there is a charge transfer from the hæmoglobin to the oxygen molecule, that is, some delocalization of one of the d-electrons of the ferrous towards the oxygen. This was meant as a starting approximation, the details to be settled by some physical measurements concerning the electronic structure. There are no obvious grounds why the resulting structure could not be diamagnetic. If this would not agree with a certain conventional definition of oxidation number then this would only show that this definition is no longer useful in this case. This is perhaps not surprising, because the O⁻₂ ion has itself an unpaired spin unlike the common anions such as OH⁻, CN⁻, which are all diamagnetic. This does, therefore, involve the more complicated problem of the interaction of the two magnetic ions when they come close together.