2001 Fiscal Year Final Research Report Summary
Controlling the ground-state spin-multiplicities of open-shell π-radicals by use of σ-bonds.
| Project/Area Number |
12640524
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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 |
Organic chemistry
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| Research Institution | Yokohama City University |
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Principal Investigator |
TUKADA Hideyuki Yokohama City University, Graduate School of Integrated Science, Associate Professor, その他の独立研究科, 助教授 (40171970)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Quintet / molecular magnetism / spin alignment / hyperconjugation / Nitrene / π-σ-π interaction / EPR / DFT |
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| Research Abstract |
Spin-alignment in radicals bearing two open-shell sites (nitrenes) intervened with σ-bonds has been investigated.
1. N-(2-Methoxycarbonyl-2-yloethyl)(3-nitrenophenyl)aminyl was photochemically generated at cryogenic temperatures, and the EPR spectrum was obtained. The quintet disappeared over 5K due to the ring-closure in the parts of 1,3-biradical. The average of activation energies for the process was estimated to be 3 kJ/mol.
2. Quintet dinitrenes, trans-1, 4-cyclohexyiene- and 1,3-adamanthylene-bis-(ρ-nitrenyl-benzene), were observed by EPR spectroscopy. Energy gaps between a singlet and a quintet for these molecules were 138 and 300 J/mol, respectively. According to DFT calculations π-σ-π hyperconjugative interactions destabilize the quintet. These facts indicate that spin-alignment by the through bond mechanism is effective up to four methylene units.
3. Derivatives of di(nitrenophenvl)methane in which hydrogen atoms in the methylene unit are replaced respectively by methyl and trifluoromethyl substituents were studied. The former indicated large anti-ferromagnetic interaction between the nitrenes, but the latter showed weak one.
4. 2,7-Disubstituted dinitrenes derived from 9,9,10,10-tetramethyl-9,10-dihydro-anthracene and 9,10-ethno-9,10-dihydroanthracene were investigated, and found that the mechanism for spin-alignment in these molecules are different as reflect the difference in spatial arrangement of the two open-shell sites.
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Research Products
(8 results)
