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Magnetic properties of organic free-radicals and charge-transfer complexes at low temperatures

Research Project

Project/Area Number 02453012
Research Category

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

Allocation TypeSingle-year Grants
Research Field 物理化学一般
Research InstitutionOsaka University

Principal Investigator

SORAI Michio  Osaka University, Faculty of Science, Professor, 理学部, 教授 (50028172)

Project Period (FY) 1990 – 1991
Project Status Completed (Fiscal Year 1991)
Budget Amount *help
¥7,200,000 (Direct Cost: ¥7,200,000)
Fiscal Year 1991: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1990: ¥5,800,000 (Direct Cost: ¥5,800,000)
KeywordsOrganic Free-radical / Molecular Ferromagnet / Mixed-valence Complex / Magnetic Properties / Heat Capacity / Charge-transfer Complex / Phase Transition / Tunnel-splitting / 有機金属錯体 / 磁化率
Research Abstract

Magnetic properties of substances have been interpreted on the basis of either of two models : one is the itinerant-electron model for delocalized-electron systems and the other is the Heisenberg model for localized-electron systems. Organic free-radicals and charge-transfer complexes, in which the unpaired electron is not localized on a particular atom but delocalized over many atoms in a molecule to a great extent, belong to an intermediate category between the two models. Magnetic properties of these radicals have so far been described as a perturbation from the two extreme models. Main purpose of the present research project was to elucidate magnetic properties of organic free-radicals and charge-transfer complexes on the basis of precise heat capacity and magnetic susceptibility measurements at low temperatures.
Compounds for which heat capacity measurements were made by adiabatic calorimeters involve (1) charge-transfer molecular ferromagnets, decamethylferrocenium-TCNE and decame … More thylferrocenium-TCNQ, (2) pure organic free-radicals, MOTMP and AOTMP, (3) charge-transfer complex TTF-CA that shows the ionicneutral phase transition, (4) binuclear mixed-valence complex, diiodobiferrocenium triiodide, and (5) mixed-metal coordination compounds, MnCu (obbz) H_2O, MnCu (obbz) 5H_2O, and NBu_4[CuCr (Ox) _3].
All the magnetic compounds exhibited a phase transition peak arising from magnetic ordering and a heat capacity anomaly due to the short-range order effect. By applying the spin-wave theory to temperature dependence of the magnetic heat capacities at low temperatures, the dimensionality of the spin-lattice and the nature of the ordered spin state were determined. The spin-spin interaction in the radical complexes has been proved to be described by the Heisenberg model, in which only the exchange integral parameter is effectively modified. Observation of a Schottky anomaly in the mixed-valence complex, 1', l"'-diiodobiferrocenium triiodide, predicts that the intramolecular electron transfer occurs by a tunnel-mechanism. Less

Report

(3 results)
  • 1991 Annual Research Report   Final Research Report Summary
  • 1990 Annual Research Report
  • Research Products

    (25 results)

All Other

All Publications (25 results)

  • [Publications] M.Nakano: "Heat Capacity of the Ferromagnetic molecular Charge-transfer Complex,Decamethylferrocenium Tetracyanoethenide:Ising-like Property of the Magnetic Interaction" Chemical Physics Letters. 169. 27-30 (1990)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] H.Sugimoto: "Organic Ferromagenetism and Anrtferromagunetism of 4-Metnacryloyloxy-2,2,6,6-tetramethylpiperidin-l-oxyl and 4-Acryloyloxy-2,2,6,6-tetramethylpiperdin-l-pxyl" Chemistry Letters. 2095-2098 (1991)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] H.Nakano: "Heat Capacity of the Mixed-valence Compound,l',l'"-Diiodo-biferrocenium Triiodide:A Molecular Quantum Paraelectric" Chemical Physics Letters,. (1992)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] K.Inoue: "Heat Capacity of the Antiferromagnetic Mixed-metal Dinuclear Cpmplex,MnCu(obbz)・5H_2 O" Joural of Physics and Chemistry of Solids.

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] N.Ohmae: "Metamagnetic Phase Transition of the Organic Free-radical Crystal,MOTMP,and Antiferromagnetic Phase Transition of the Organic Free-radical Crystal,AOTMP" Journal of Physics and Chemistry of Solids.

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] K.Asano: "Ferromagnetic Phase Transition of the Mixed-metal Complx,NBu_4[CuCr(ox)_3]" Journal of Physics and Chemistry of Solids.

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] M. Nakano et al.: "Heat Capacity of the Ferromagnetic Molecular Chargetransfer Complex, Decamethylferrocenium Tetracyanoethenide : Ising-like Property of the Magnetic Interaction" Chemical Physics Letters. 169. 27-30 (1990)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] H. Sugimoto et al.: "Organic Ferromagnetism and Antiferromagnetism of 4-Methacryloyloxy-2-, 2, 6, 6-tetramethylpiperidin-1-oxyl and 4-Acryloyloxy-2, 2, 6, 6-tetramethylpiperidin-l-oxyl" Chemistry Letters. 2095-2098 (1991)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] M. Nakano et al.: "Heat Capacity of the Mixed-valence Compound, 1', 1'"-Diiodobiferrocenium Triiodide : A Molecular Quantum Paraelectric" Chemical physics Letters. (1992)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] K. Inoue et al.: "Heat Capacity of the Antiferromagnetic Mixed-metal Dinuclear Complex, MnCu (obbz). 5H_2O" Journal of physics and Chemistry of Solids. (1992)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] N. Ohmae et al.: "Metamagnetic Phase Transition of the Organic Free-radical Crystal, MOTMP, and Antiferromagnetic Phase Transition of the Organic Free-radical Crystal AOTMP" Journal of Physics and chemistry of solids. (1992)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] K. Asano et al.: "Ferromagnetic Phase Transition of the Mixed-metal complex, NBu_4[CuCr (ox)_3]" Journal of Physics and Chemistry of solids. (1992)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] T. Kawamura et al.: "Heat Capacity of the Charge-transfer Complex Tetrachiafulvalene-chloranil (TTF-CA)" Journal of Physics and Chemistry of Solids. (1992)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1991 Final Research Report Summary
  • [Publications] H.Sugimoto: "Organic Ferromagnetism and Antiferromagnetism of 4‐Methacryloyloxy‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl and 4‐Acryloyloxy‐2,2,6,6‐tetramethylpiperidin‐1‐oxyl" Chemistry Letters. 2095-2098 (1991)

    • Related Report
      1991 Annual Research Report
  • [Publications] M.Nakano: "Heat Capacity of the Mixed‐Valence Compound,l^1,l^1,‐Diiodo‐biferrocenium Triiodie:A Molecular Quantum Paraelectric" Chemical Physics Letters. (1992)

    • Related Report
      1991 Annual Research Report
  • [Publications] K.Inoue: "Heat Capacity of the Antiferromagnetic Mixed‐Metal Dinuclear Complex,MnCu(obbz)・5H_2O" Journal of Physics and Chemistry of Solids. (1992)

    • Related Report
      1991 Annual Research Report
  • [Publications] N.Ohmae: "Metamatnetic Phase Transition of the Organic Free Radical Crystal,MOTMP,and Antiferromagnetic Phase Transition of the Organic Free Radical Crystal,AOTMP" Journal of Physics and Chemistry of Solids. (1992)

    • Related Report
      1991 Annual Research Report
  • [Publications] K.Asano: "Ferromagnetic Phase Transition of the Mixed‐Metal Complex,NBu_4[CuCr(ox)_3]" Journal of Physics and Chemistry of Solids. (1991)

    • Related Report
      1991 Annual Research Report
  • [Publications] T.Kawamura: "Heat Capacity of the Charge‐Transfer Complex Tetrathiafulvalene‐Chloranil(TTF‐CA)" Journal of Physics and Chemistry of Solids. (1992)

    • Related Report
      1991 Annual Research Report
  • [Publications] M.Nakano: "Heat capacity of the ferromagnetic molecular chargeーtransfer complex,decamethylferrocenium tetracyanoethenide:Isingーlike property of the magnetic interaction" Chem.Phys.Lett.169. 27-30 (1990)

    • Related Report
      1990 Annual Research Report
  • [Publications] H.Sugimoto: "Organic ferromagnetism of 4ーmethacryloyloxyー2,2,6,6ーtetramethylーpiperidinーlーoxyl and antiferromagnetism of 4ーacryloylowyー2,2,6,6ーtetramethylーpiperidineーlーoxyl" J.Chem.Soc.,Chem.Commun.(1991)

    • Related Report
      1990 Annual Research Report
  • [Publications] K.Inoue: "Ferromagnetic phase transition in the mixedーmetal dinuclear complex,MnCu(obbz)・H_2O" J.Phys.Chem.Solids. (1991)

    • Related Report
      1990 Annual Research Report
  • [Publications] M.Nakano: "Ferromagnetic and antiferromagnetic molecular chargeーtransfer complexes,[Fe(C_5(CH_3)_5)_2]TCNE and [Fe(C_5(CH_3)_2]TCNO" J.Phys.Chem.Solids. (1991)

    • Related Report
      1990 Annual Research Report
  • [Publications] K.Inoue: "Antiferromagnetic phase transition in the mixedーmetal dinuclear complex,MnCu(obbz)・5H_2O" J.Phys.Chem.Solids. (1991)

    • Related Report
      1990 Annual Research Report
  • [Publications] M.Sorai: "Heat capacity and phase transition of the spinーcrossover comlex,[Cr(depe)_2I_2]" J.Phys.Chem.Solids. (1991)

    • Related Report
      1990 Annual Research Report

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Published: 1990-04-01   Modified: 2016-04-21  

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