| Project/Area Number |
17350031
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | The Institute of Physical and Chemical Research (2007)
Institute for Molecular Science (2005-2006) |
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Principal Investigator |
TSUKASA Matsuo The Institute of Physical and Chemical Research, Functional Elemento-Organic Chemistry, Deputy Unit Leader (90312800)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥15,100,000 (Direct Cost: ¥14,500,000、Indirect Cost: ¥600,000)
Fiscal Year 2007: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
Fiscal Year 2006: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2005: ¥10,500,000 (Direct Cost: ¥10,500,000)
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| Keywords | post-metallocene / titanium / zirconium / phenoxide ligand / activation of small molecules / carbon monoxide / carbon dioxide / dinitrogen molecule / 4族遷移金属 / ヒドリド錯体 / ハフニウム / 4族遷移金属錯体 / チオラート配位子 / キレート効果 / 小分子の活性化 |
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| Research Abstract |
A variety of group 4 metal complexes incorporating multidentate phenoxide ligands have been synthesized and their molecular structures have been confirmed by X-ray crystallography. The electronic and steric properties, and chelating effect of the new donating system have been examined for the construction of highly reactive metal species. We have succeeded in activation of small molecules such as dihydrogen, dinitrogen, carbon monoxide, and carbon dioxide by using the early transition metal complexes having multidentate phenoxide ligands. For example, the zirconium complexes supported by the anisole-bridged bis (phenoxide) ligands serve as an easily recycled auxiliary for converting H_2 and CO into allene and hexamethyldisiloxane under mild conditions. Hydrogenolysis of the zirconium benzyl complexes followed by treatment with CO led to formation of oxo-bridged complexes and allene. Deoxygenation of the resulting oxo-bridged complexes with trimethylsilyltrifluoromethanesulfonate and trimethylsilyl chloride and subsequent treatment with benzylmagnesium chloride re-formed the starting benzyl complexes. We have also shown that CO_2 is catalytically converted into methane and siloxanes via bis (silyl)acetals with a mixture of a zirconium alkyl phenoxide complex and B (C_6F_5)_3. Our method for catalytic reduction of CO_2 offers some significant advantages, since it proceeds under mild conditions and permits complete reduction of CO_2 to CH_4. Another curious aspect of this system is the formation of functional siloxane materials from CO_2 and hydrosilanes in chemical CO_2 fixation. We have also found that exposure of a solution of the niobium hydride complex supported by a tripodal triaryloxide ligand with N_2 gas resulted in the formation of nitride complex and H_2 with concomitant cleavage of the dinitrogen triple bond. The nitride ligands undergo alkylation with MeI in a stepwise fashion, resulting in formation of a bis (imide) complex via a nitride imide complex.
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