| Project/Area Number |
14078204
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | University of Tsukuba |
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Principal Investigator |
SEKIGUCHI Akira University of Tsukuba, Graduate School of Pure and Applied Sciences, Professor, 大学院数理物質科学研究科, 教授 (90143164)
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| Project Period (FY) |
2002 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥25,600,000 (Direct Cost: ¥25,600,000)
Fiscal Year 2005: ¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 2004: ¥6,800,000 (Direct Cost: ¥6,800,000)
Fiscal Year 2003: ¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 2002: ¥6,000,000 (Direct Cost: ¥6,000,000)
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| Keywords | Element Chemistry / Heavier Group 14 Element / Cluster / Cation / Radical / Aromaticity / Silicon / Functional materials / 高周期14族元素 / 高周期14族元素多重結合 / 高周期14族元素芳香族化合物 / 高周期14族元素カチオン種 / 高周期14族元素アニオン種 / 高周期14族元素ラジカル種 / 高周期14族元素多重結合化合物 / 不飽和小員環化合物 / 有機ゲルマニウム化合物 / ゲルマニウムカチオン / 芳香族化合物 / ホモ芳香族化合物 |
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| Research Abstract |
The chemistry of the stable ionic species of heavier group 14 elements has been studied, including both cationic and anionic species together with radical species. The electronic and crystal structural features of these ionic species, both in the solid state and in solution, have been investigated by the experimental and computational study.
1. The highly crowded 3,3-bis(di-tert-butylmethylsily1)-1,2-bis(tri-tert-butylsilyl)cyclotrisilene, an unsaturated three-membered compound with an Si=Si bond, was treated with triphenylmethylium tetraarylborate to produce (di-tert-butylmethylsilyl)bis(tri-tert-butylsilyl)cyclotrisilenylium ion, representing the first isolable silicon congener of the cyclopropenylium ion. The X-ray crystal structure and spectral data show that the cyclotrisilenylium ion is not only a free silyl cation but also a 2a electron aromatic species with delocalization of the positive charge over the three-membered skeleton.
2. The heavy cyclobutadiene dianions, tetrakis(di-tert-butylmethylsily1)-1,2-disila-3,4-digermacyclobutadiene dianion and tetrakis(di-tert-butylmethylsilyl)tetrasilacyclobutadiene dianion, have been synthesized by the reductive dehalogenation of the corresponding precursors with potassium graphite. The cyclobutadiene dianions were found to be nonaromatic by their structural features and the lack of diatropic ring current effects.
3. The one-electron oxidation reaction of tris[di-tert-butyl(methyl)silyl]silyl and germyl anions with dichlorogermylene dioxane complex resulted in the formation of stable tris[di-tert-butyl(methypsilyl]sily1 and germyl radicals. The crystal structures of both silyl and germyl radicals showed a completely planar geometry around the radical centers. The EPR spectra indicate the a-character of both radicals, corresponding to a planar geometry and sp2 hybridization of the radical centers.
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