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1989 Fiscal Year Final Research Report Summary

The Rotational Orientation Angles of Axial Ligands in Low-Spin Fe(III) Heme Complexes As Determined from Frozen-Solution Samples

Research Project

Project/Area Number 63571026
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field Physical pharmacy
Research InstitutionTeikyo University

Principal Investigator

SATO Mitsuo  Biophys. Div., Fac. Pharm. Sci., Prof., 薬学部, 教授 (70101714)

Project Period (FY) 1988 – 1989
KeywordsLow-spin Fe(III) heme complex / Rotational orientation of rhombic field / Rotational orientation of axial ligand / Iron-57 hf splitting / Relative orientations of g and hf tensors / Pー450モデル錯体
Research Abstract

Hyperfine (hf) splittings due to the ^<57>Fe nucleus (I=1/2) have been observed in frozen-solution ESR measurements on a series of low-spin Fe(III) heme complexes, Fe(TPP)L_1L_2, where TPP =tetraphenylporphine dianion, L_1 = RS^-, L_2 = MeOH, DMF, and RSH, and R = Et, n-Pr, i-Pr, n-Bu, s-Bu, and t-Bu. The hf splitting (A_<(i)>) values of the g_i absorption peaks (i = X, Y, Z) are analyzed within the framework of a low-symmetry (C_2) crystal field model to determine the rotational orientation angle (phi) of the axes of rhombic component field and that (phi_l) of the axial thiolato ligand plane (Fe-S-C plane) with the approximation of phi_l = phi. It is found that phi_l varies from 6 to 37゚ depending upon the thiolato ligand (RS^-), the 6th axial ligand (L_2), and the solvent system (CH_2Cl_2 - MeOH, DMF-MeOH, or CH_2Cl_2-RSH), but with no clear correlation between phi_l and RS^-. However, phi_l correlates well with the energy splittings in the three t_2 orbitals: phi_l increases as the tetragonal splitting decreases or as the rhombic splitting and crystal field rhombicly increase. These results suggest that two major factors, namely, steric and electronic effects, influence the axial ligand orientation. The observed angles phi_l = 6-37゚ are the results of the two effects.

  • Research Products

    (13 results)

All Other

All Publications (13 results)

  • [Publications] M.Sato: "Electron Spin Resonance Studies of Low-Spin Ferric Heme Complexes in Frozen Solutions.Iron-57 Hyperfine Splittings and the Angular Orientation of Rhombic Field" Nippon Kagaku Kaishi. 522-530 (1988)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Tohara: "Photoreduction of Hydroxotetramesitylporphinatoiron(III)in Aromatic Hydrocarbons and the Concurrent Generation of Hydroxyl Radical" Chem.Let.,. 153-156 (1989)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] N.Kobayashi: "Mossbauer and ESR Spectroscopy of Tetranitro-and Tetraaminophthalocyaninatoiron" Makromol.Chem.,. 10. 1-4 (1989)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Itoh: "Deoxygenation of Oxiran Compounds to Olefins by [Fe_4S_4(SC_6H_5)_4]^<2-> in the Presence of NaBH_4" Tetrahedron Let.,. 30. 6387-6388 (1989)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Sato: "Rotational Angular Orientation of Axial Thiolato Ligand in Low-Spin P-450 Model Complexes" J.Pharmacobio-Dyn.,. 13. s-5 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] J.Takeda: "A New Synthesis of Octaarylporphyrins:Naturally Occuring Porphyrin Mimics" Chem.Pharm.Bull.,. 38. 264-266 (1990)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M. Sato, T. Otsuka, T. Ohya: "Electron Spin Resonance Studies of Low-Spin Ferric Heme Complexes in Frozen Solutions. Iron-57 Hyperfine Splittings and the Angular Orientation of Rhombic Crystal Field" Nippon Kagaku Kaishi, 522, 1988.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A. Tohara, M. Sato: "Photoreduction of Hydroxotetramesitylporphinato)iron(III) in Aromatic Hydrocarbons and the Concurrent Generation of Hydroxyl Radical" Chemistry Letters, 153, 1989.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T. Itoh, T. Nagano, M. Sato, M. Hirobe: "Deoxygenation of Oxiran Compounds to Olefins by [Fe_4S_4(SC_6H_5)_4]^<2-> in the Presence of NaBH_4" Tetrahedron Letters, 30, 6387, 1989.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] N. Kobayashi, H. Konami, T. Ohya, M. Sato, H. Shirai: "Mossbauer and ESR Spectroscopy of Tetranitro- and Tetraaminophthalocyaninatoiron" Makromol. Chem., 10, 1, 1989.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M. Sato, T. Ohya: "Rotational Angular Orientation of Axial Thiolato Ligand in Low-Spin P-450 Model Complexes" J. Pharmacobio-Dyn., 13, s-5, 1990.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] J. Takeda, T. Ohya, M. Sato: "A New Synthesis of Octaarylporphyrins: Naturally Occurring Porphyrin Mimics" Chem. Pharm. Bull., 38, 264, 1990.

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T. Ohya, J. Takeda, N. Kobayashi, M. Sato: "Bonding Character in Tetracoordinate (Phthalocyaninato) - iron(II) Complexes with Electron-Releasing Substituents As Studied by Mossbauer Spectroscopy" Inorg. Chem.

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1993-03-26  

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