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1998 (1)
1Author    Christian Kollmar, SighartF. Fischer, MichaelC. BöhmRequires cookie*
 Title    MO-Theoretical Studies on a Model Complex for Deoxymyoglobin  
 Abstract    The origin of the displacement of the Fe atom in deoxymyoglobin with respect to the porphyrin plane in the high-spin state is examined by a qualitative molecular orbital (MO) analysis on the extended Hückel level. We find that attachment of a fifth ligand (imidazole in our model complex) to Fe(II)porphyrin favors the out-of-plane shift due to a strengthening of the bonding interaction between Fe and the nitrogen of the imidazole ligand. This results in a high-spin (5 = 2) ground state with Fe shifted out-of-plane for the five-coordinate complex instead of an intermediate spin ground state (5=1) with Fe lying in the plane for four-coordinate Fe(II)porphyrin. The relative energies of the different spin states as a function of the distance between Fe and the porphyrin plane are evaluated using an ROHF (restricted open shell Hartree-Fock) version of an INDO (intermediate neglect of differential overlap) method. We observe a level crossing between high-spin and intermediate spin states whereas the low-spin (5 = 0) state remains always higher in energy. 
  Reference    Z. Naturforsch. 53a, 755—765 (1998); received July 1 1998 
  Published    1998 
  Keywords    Metalloporphyrines, Electronic Structure, Structural Preferences, Molecular Orbital Model 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0755.pdf 
 Identifier    ZNA-1998-53a-0755 
 Volume    53