title: NMR investigation of the electric properties and magnetic states of hemes and hemoproteins : the S = 2 state in ferrous porphyrins.
abstract: The proton NMR data of a synthetic model of deoxy-myoglobin and hemoglobin show one that:(i) the ground state of the high spin iron (II) complex must be described by at least two electronic levels separated by ca.200 cm-1 and resulting from the removal of the degeneracy of the 5E level; (ii) this in-plane rhombic distorsion is directed towards the methine bridges of the porphyrin ring. It is proposed that the rhombicity results from specific interactions of the lambda orbitals of the axial base with the iron d lambda orbitals.
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D006418:Heme / Q000032:analysis*; D006420:Hemeproteins / Q000032:analysis*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008280:Magnetics; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000032:analysis*; D011487:Protein Conformation; D011789:Quantum Theory
chemical_list: D006420:Hemeproteins; D011166:Porphyrins; D006418:Heme