Oxyhemoglobin, with an 02 bound to iron, is a low-spin

Chapter , Problem 81AE

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Problem 81 AE

Oxyhemoglobin, with an 02 bound to iron, is a low-spin Fe(ll) complex: deoxyhemoglobin, without the 02 molecule, is a high-spin complex, (a) Assuming that the coordination environment about the metal is octahedral, how many unpaired electrons are centered on the metal ion in each case? (b) What ligand is coordinated to the iron in place of 02 in deoxyhemoglobin? (c) Explain in a general way why the two forms of hemoglobin have different colors (hemoglobin is red. whereas deoxyhemoglobin has a bluish cast), (d) A 15-minute exposure to air containing 400 ppm of CO causes about 10% of the hemoglobin in the blood to be converted into the carbon monoxide complex, called carboxyhemoglobin. What does this suggest about the relative equilibrium constants for binding of carbon monoxide and 02 to hemoglobin’ (e) CO is a strong-field ligand. What color might you expect carboxyhemoglobin to be?