[mythonline]

Hi,

I am trying to understand why the iron's oxidation level in deoxyhaemoglobin is +2, I mean it is bonded to 4 pyrrole rings on the nitrogen (the book showing 2 full lines to 2 of them, and 2 broken lines to the other 2) , and 1 bond to the proximal histidine, so how is it exactly +2? if the broken lines are not covalent bonds, then it should be +3?

Could someone please explain all the bonds that the iron atom has in this molecule?

[discodermolide]

Professor Google says look at this page:
http://en.wikipedia.org/wiki/Hemoglobin

[mythonline]

Professor Google says look at this page:
http://en.wikipedia.org/wiki/Hemoglobin

that was the first place I was looking. add about 10 more sites and 2 biochemistry books and none of them explains why the oxidation level is +2.

[fledarmus]

That +2 is the charge on the iron atom. Neutral iron has ...4s₂3d₆. Remove the two 4s electrons to get Fe²⁺, then three covalent bonds (with nitrogen sharing a pair) and two coordinate bonds (with nitrogen donating electron pairs) gives 13 electrons, filling 4s and 4p shells, and half-filling the 3d shells. This is reasonably stable for iron(II), slightly more stable even than iron(III) would be in this molecule.

[mythonline]

That +2 is the charge on the iron atom. Neutral iron has ...4s₂3d₆. Remove the two 4s electrons to get Fe²⁺, then three covalent bonds (with nitrogen sharing a pair) and two coordinate bonds (with nitrogen donating electron pairs) gives 13 electrons, filling 4s and 4p shells, and half-filling the 3d shells. This is reasonably stable for iron(II), slightly more stable even than iron(III) would be in this molecule.

thanks