2018 Fiscal Year Research-status Report
Binuclear Sandwiches of the Main Group Elements
| Project/Area Number |
18K05137
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| Research Institution | University of Tsukuba |
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Principal Investigator |
Lee Vladimir 筑波大学, 数理物質系, 講師 (90375410)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Keywords | cluster / group 14 element / group 13 element / binuclear sandwich / bis(pyramidane) / cyclobutadiene dianion / NMR spectroscopy / X-ray crystallography |
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| Outline of Annual Research Achievements |
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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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
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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| Strategy for Future Research Activity |
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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| Causes of Carryover |
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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[Journal Article] [Pd(4-R3Si-IPr)(allyl)Cl], a Family of Silyl-Substituted Pd－NHC Complexes: Catalytic Systems for the Buchwald－Hartwig Amination2019
Author(s)
N. Fukaya, T. Mizusaki, K. Hatakeyama, Y. Seo, Y. Inaba, K. Matsumoto, V. Ya. Lee,* Y. Takagi, J. Kuwabara, T. Kanbara, Y.-K. Choe, J.-C. Choi
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Journal Title
Organometallics
Volume: 38
Pages: 376-384
DOI
Peer Reviewed / Int'l Joint Research
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[Presentation] Pyramidanes2018
Author(s)
V. Ya. Lee,* O. A. Gapurenko, A. Sekiguchi, R. M. Minyaev, V. I. Minkin
Organizer
The 14th International Kyoto Conference on New Aspects of Organic Chemistry (IKCOC-14), Kyoto, Japan
Int'l Joint Research
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