1991 Fiscal Year Final Research Report Summary
Mossbauer Spectroscopic Studies of Spin-Crossover Iron Complexes
| Project/Area Number |
02640482
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
無機・錯塩・放射化学
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| Research Institution | Keio University |
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Principal Investigator |
INOUE Hidenari Keio University, Faculty of Sci. & Tech., Prof., 理工学部, 教授 (60051752)
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| Co-Investigator(Kenkyū-buntansha) |
金 萬九 慶應義塾大学, 理工学部, 助手
SUZUKI Koji Keio University, Sci. & Tech., Ass. Prof., 理工学部, 専任講師 (80154540)
KIM Man-Goo Keio University, Sci. & Tech., Ass.
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| Project Period (FY) |
1990 – 1991
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| Keywords | Moessbauer spectroscopy / Spin-crossover / Mixed ligand complexes / Iron complexes / Magnetic transition / Metallochlorophylls / Prussian blue analogs |
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| Research Abstract |
A series of iron (II, III) complexes of various ligands with an intermediate ligand-field strength have been prepared to investigate the spin-crossover transition induced by temperature or pressure. The influence of the mixed ligand coordination of 2, 2'-bipyridine (bpy) and 1, 10-phenanthroline (phen) to a central iron (II) ion is discussed on the basis of the temperature variation of ^<57>Fe Mossbauer spectra and magnetic moments. The mixed coordination in [Fe(bpy)(phen)(NCS)_2] has been demonstrated to make the spincrossover transition more gradual. The spin-crossover transition temperature is affected by the electronic property as well as the stracture of the ligands coordinated to the central iron (II) ion. The spin-crossover phenomenon or the spin-equilibrium in metallochlorophylls and Prussian blue analogs has been also studied by ^<57>Fe Mossbauer, NMR and X-ray photoelectron spectroscopy. The central iron (III) ion of (pheophytinato) iron (III) chloride in the high-spin state is autoreduced to the ferrous low-spin state upon the axial coordination of pyridine and its derivatives. The spectral measurements of heattrated Prussian blue have revealed that a new mixed-valence state is produced by thermally flipping the cyano ligand and quenching the flipped cyano ligand to liquid nitrogen temperature. Mbssbauer spectral experiments under higher pressure are in progress to elucidate the mechanism of the spin-crossover transition induced by increasing pressure.
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