[kriggy]

Hi guys, studying for exams and this part troubles me:
"Magnetochemical measurements of colorless deoxy-hemerythrine suggest Fe(II) in high spin state with 4 unpaired electrons. On the other hand, red-purple oxy-hemerytrine which bonds one molecule of O₂ to one Fe-dimer cosnsist of 2 high spine Fe(III) centres with strong antiferromagnetic interaction. The absence of strong light absorption in deoxy-Hemerythrine is suggested by the fact that Fe centers are bound to the protein. We could expect the colour in case of presence of porphyrine Π-electron system. The colour of oxo-hemerythrine is absence of macrocyclic ligand is related to ligand to metal charge transfer."

Does anyone has idea why there is strong LMCT in oxy-Hr but not in deoxy-Hr?

And what exactly is the antiferromagnetic interaction? Does it mean that the high spin metal centers are close to each other so they act as if their spins were all paired together therefore acting as diamagnetic?