| 研究課題/領域番号 |
18K05137
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| 研究機関 | 筑波大学 |
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研究代表者 |
Lee Vladimir 筑波大学, 数理物質系, 講師 (90375410)
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| 研究期間 (年度) |
2018-04-01 – 2021-03-31
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| キーワード | cluster / group 14 element / group 13 element / binuclear sandwich / bis(pyramidane) / cyclobutadiene dianion / NMR spectroscopy / X-ray crystallography |
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| 研究実績の概要 |
The goal of this project is the development of synthetic approaches for the preparation of a novel class of the highly strained polyhedral clusters, bis- and poly(pyramidanes) and bis- and poly(housenes). Given their non-classical structures, such bi- and poly(nuclear) sandwiches of the main group elements are very interesting objects for fundamental studies, both experimental and computational, to reveal their peculiar structural features and unusual bonding situations. On the other hand, such polyhedral clusters could serve as very promising precursors for novel type of ceramics and nanostructural objects in material science.
In accord with the originally proposed plan, during the first year of the project we successfully synthesized a series of the neutral pyramidanes with the group 13 element at the apex of the square-pyramid. These compounds were readily prepared by the straightforward reaction of the corresponding cyclobutadiene dianion derivatives with the group 13 element halides EX3 (E = group 13 element). Reaction conditions (solvents, temperature, ratio of reagents) were optimized to maximize the yields of target pyramidanes. The structures of all synthesized pyramidanes were carefully studied both experimentally (X-ray, NMR) and computationally (high-level DFT calculations), and they were compared with the structures of the previously prepared pyramidanes of the group 14 elements.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
During the first year of the project, our original plan was successfully fulfilled and the planned synthetic goals were realized. Thus, for example, a series of the target neutral borapyramidanes RB[C4(SiMe3)4] (R = Cl, Br, Ph, H) was quantitatively prepared by the coupling reaction of the readily available cyclobutadiene dianion dilithium salt {[C4(SiMe3)4](2-)}2Li+ with boron dihalides RBX2 (X = Cl, Br). All novel hybrid group 13/group 14 pyramidanes, namely borapyramidanes, were fully structurally characterized, and their apex-to-base bonding situations were comprehensively studied computationally.
Thus, during its first year, the project was running rather smoothly without any troubles and in accord with the originally proposed research plan and schedule.
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| 今後の研究の推進方策 |
For the following second year of the project, we will attempt the synthesis of the bis(pyramidanes), as the bi(nuclear) sandwiches of the main group elements, as well as bis(housenes), utilizing previously synthesized mono(pyramidanes) and mono(housenes). Bis(pyramidanes) are expected to be prepared by the reductive dehalogenation of (halobora)pyramidane precursors with alkali or alkaline-earth metals, whereas bis(housenes) can be prepared by the reductive dehalogenation and coupling of the corresponding mono(housene) precursors with alkali or alkaline-earth metals. The structures and reactivity of these newly prepared clusters will be studied both experimentally and computationally, especially effects of substituents and skeletal atoms on the stability of these systems.
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| 次年度使用額が生じた理由 |
For the first year of the project, the originally proposed amount was 1.600.000 yen, and actually 1.337.635 yen were used. It is caused by the changes in our original plan to purchase some equipment and reagents, because it was possible to perform our experiments without such equipment and reagents. Money remaining after the first year of the project, 262,365 yen, was transferred to the second year of the project, and will be used to purchase chemical reagents.
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