2003 Fiscal Year Final Research Report Summary
SYNTHESIS AND PROPERTIES OF IRON(III) PORPHYRIN COMPLEXES WITH NOVEL SPIN STATE
| Project/Area Number |
14540521
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic chemistry
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| Research Institution | TOHO UNIVERSTIY |
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Principal Investigator |
NAKAMURA Mikio TOHO UNIVERSTIY, SCHOOL OF MEDICINE, PROFESSOR, 医学部, 教授 (20112914)
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| Co-Investigator(Kenkyū-buntansha) |
IKEZAKI Akira TOHO UNIVERSTIY, SCHOOL OF MEDICINE, RESEARCH ASSOCIATE, 医学部, 助手 (80297639)
OHGO Yoshiki TOHO UNIVERSTIY, SCHOOL OF MEDICINE, ASSITENT PROFESSOR, 医学部, 講師 (40287496)
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| Project Period (FY) |
2002 – 2003
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| Keywords | PORPHYRIN / IRON COMPLEXES / SPIN CROSSOVER / SADDLED DEFORMATION / ^<13>C NMR / EPR / MOSSBAUER / SQUID |
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| Research Abstract |
i)By the coordination of weak THF ligand to the iron(III) complexes with highly ruffled porphyrin ring, we were able to prepare essentially pure intermediate spin complexes. The ^<13>C NMR measurements have revealed that these complexes adopt a novel (d_<xz>, d_<yz>)^3(d_<xy>)^1(d_z^2)^1 electron configuration; the intermediate spin iron(III) complexes reported previously are believed to have (d_<xy>)^2(d_<xz>, d_<yz>)^2(d_z^2)^1 electron configuration.
ii)The electron configuration of the low spin (S = 1) manganese(III) complexes with highly ruffled porphyrin ring has also been examined. In contrast to the case of the corresponding iron(III) complexes, they have shown a common (d_<xy>)^2(d_<xz>, d_<yz>)^2 electron configuration. The result suggests, that the d_π orbitals are located higher in energy than the d_<xy> orbital in the case of manganese complexes even if the porphyrin ring is highly ruffled.
iii)The iron(III) complex with highly saddled porphyrin ring was treated with pyridine and substituted pyridine. The magnetic properties of the bis(pyridine) complex thus formed were examined by ^1H NMR, ^<13>C NMR, EPR, and Mossbauer spectroscopy as well as X-ray crystallography and SQUID magnetometry. While the complex showed a spin crossover between the S = 1/2 and S = 3/2 spin states in solution, the same complex maintained the S = 1/2 in the solid. The X-ray crystallographic measurements at different temperatures have revealed that the complex is tightly packed in the crystal lattice. Consequently, there is little space for the axial ligand to change the Fe-Ligand bond length. On the basis of these results, we have concluded that the enough cavity is necessary around the axial ligand for the complex to show the spin crossover process.
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