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Yoshiaki Nishibayashi - One of the best experts on this subject based on the ideXlab platform.
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structural characterization of molybdenum Dinitrogen complex as key species toward ammonia formation by dispersive xafs spectroscopy
Physical Chemistry Chemical Physics, 2020Co-Authors: Akira Yamamoto, Kazuya Arashiba, Kazunari Yoshizawa, Yoshiaki Nishibayashi, Hiromasa Tanaka, Shimpei Naniwa, Kazuo Kato, Hisao YoshidaAbstract:The structural characterization of a hardly-isolatable molybdenum–Dinitrogen complex bearing a PNP-type pincer ligand, which is assumed to be a key reactive complex in the stoichiometric transformation of a molybdenum triiodide complex [MoI3(PNP)] into the corresponding molybdenum nitride complex under an atmospheric pressure of Dinitrogen, was carried out by using dispersive XAFS.
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catalytic nitrogen fixation via direct cleavage of nitrogen nitrogen triple bond of molecular Dinitrogen under ambient reaction conditions
Bulletin of the Chemical Society of Japan, 2017Co-Authors: Kazuya Arashiba, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Aya Eizawa, Yoshiaki NishibayashiAbstract:We have now found that molybdenum–iodide complexes bearing a PNP-pincer ligand have a higher catalytic activity than the so far reported molybdenum–Dinitrogen complexes for ammonia formation from nitrogen gas under ambient reaction conditions, up to 830 equiv being produced based on a Dinitrogen-bridged dimolybdenum complex (415 equiv of ammonia based on the molybdenum atom). This remarkable catalytic activity is induced by a novel reaction pathway, where the generation of a Dinitrogen-bridged dimolybdenum–iodide complex is a key point to promote direct cleavage of the nitrogen–nitrogen triple bond of the bridging Dinitrogen ligand in the Mo–N≡N–Mo core.
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interplay between theory and experiment for ammonia synthesis catalyzed by transition metal complexes
ChemInform, 2016Co-Authors: Hiromasa Tanaka, Yoshiaki Nishibayashi, Kazunari YoshizawaAbstract:ConspectusNitrogen fixation is an essential chemical process both biologically and industrially. Since the discovery of the first transition-metal–Dinitrogen complex in 1965, a great deal of effort has been devoted to the development of artificial nitrogen fixation systems that work under mild reaction conditions. However, the transformation of chemically inert Dinitrogen using homogeneous catalysts is still challenging because of the difficulty in breaking the strong triple bond of Dinitrogen, and a very limited number of transition metal complexes have exhibited the catalytic activity for the direct transformation of Dinitrogen into ammonia with low turnover numbers. To develop more effective nitrogen fixation systems, it is necessary to retrieve as much information as possible from the limited successful examples. Computational chemistry will provide valuable insights in the understanding of the reaction mechanisms involving unstable intermediates that are hard to isolate or characterize. We have been ...
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Catalytic transformation of Dinitrogen into ammonia and hydrazine by iron-Dinitrogen complexes bearing pincer ligand
Nature Communications, 2016Co-Authors: Shogo Kuriyama, Kazuya Arashiba, Yuki Matsuo, Kazuyuki Ishii, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Yoshiaki NishibayashiAbstract:Synthesis and reactivity of iron-Dinitrogen complexes have been extensively studied, because the iron atom plays an important role in the industrial and biological nitrogen fixation. As a result, iron-catalyzed reduction of molecular Dinitrogen into ammonia has recently been achieved. Here we show that an iron-Dinitrogen complex bearing an anionic PNP-pincer ligand works as an effective catalyst towards the catalytic nitrogen fixation, where a mixture of ammonia and hydrazine is produced. In the present reaction system, molecular Dinitrogen is catalytically and directly converted into hydrazine by using transition metal-Dinitrogen complexes as catalysts. Because hydrazine is considered as a key intermediate in the nitrogen fixation in nitrogenase, the findings described in this paper provide an opportunity to elucidate the reaction mechanism in nitrogenase.
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catalytic formation of ammonia from molecular Dinitrogen by use of Dinitrogen bridged dimolybdenum Dinitrogen complexes bearing pnp pincer ligands remarkable effect of substituent at pnp pincer ligand
Journal of the American Chemical Society, 2014Co-Authors: Shogo Kuriyama, Kazuya Arashiba, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Nobuaki Kamaru, Yoshiaki NishibayashiAbstract:A series of Dinitrogen-bridged dimolybdenum–Dinitrogen complexes bearing 4-substituted PNP-pincer ligands are synthesized by the reduction of the corresponding molybdenum trichloride complexes under 1 atm of molecular Dinitrogen. In accordance with a theoretical study, the catalytic activity is enhanced by the introduction of an electron-donating group to the pyridine ring of PNP-pincer ligand, and the complex bearing 4-methoxy-substituted PNP-pincer ligands is found to work as the most effective catalyst, where 52 equiv of ammonia are produced based on the catalyst (26 equiv of ammonia based on each molybdenum atom of the catalyst), together with molecular dihydrogen as a side-product. Time profiles for the catalytic reactions indicate that the rates of the formation of ammonia and molecular dihydrogen depend on the nature of the substituent on the PNP-pincer ligand of the complexes. The formation of ammonia and molecular dihydrogen is complementary in the reaction system.
Kazunari Yoshizawa - One of the best experts on this subject based on the ideXlab platform.
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structural characterization of molybdenum Dinitrogen complex as key species toward ammonia formation by dispersive xafs spectroscopy
Physical Chemistry Chemical Physics, 2020Co-Authors: Akira Yamamoto, Kazuya Arashiba, Kazunari Yoshizawa, Yoshiaki Nishibayashi, Hiromasa Tanaka, Shimpei Naniwa, Kazuo Kato, Hisao YoshidaAbstract:The structural characterization of a hardly-isolatable molybdenum–Dinitrogen complex bearing a PNP-type pincer ligand, which is assumed to be a key reactive complex in the stoichiometric transformation of a molybdenum triiodide complex [MoI3(PNP)] into the corresponding molybdenum nitride complex under an atmospheric pressure of Dinitrogen, was carried out by using dispersive XAFS.
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catalytic nitrogen fixation via direct cleavage of nitrogen nitrogen triple bond of molecular Dinitrogen under ambient reaction conditions
Bulletin of the Chemical Society of Japan, 2017Co-Authors: Kazuya Arashiba, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Aya Eizawa, Yoshiaki NishibayashiAbstract:We have now found that molybdenum–iodide complexes bearing a PNP-pincer ligand have a higher catalytic activity than the so far reported molybdenum–Dinitrogen complexes for ammonia formation from nitrogen gas under ambient reaction conditions, up to 830 equiv being produced based on a Dinitrogen-bridged dimolybdenum complex (415 equiv of ammonia based on the molybdenum atom). This remarkable catalytic activity is induced by a novel reaction pathway, where the generation of a Dinitrogen-bridged dimolybdenum–iodide complex is a key point to promote direct cleavage of the nitrogen–nitrogen triple bond of the bridging Dinitrogen ligand in the Mo–N≡N–Mo core.
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remarkable catalytic activity of Dinitrogen bridged dimolybdenum complexes bearing nhc based pcp pincer ligands toward nitrogen fixation
Nature Communications, 2017Co-Authors: Aya Eizawa, Yuki Matsuo, Shogo Kuriyama, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa TanakaAbstract:Intensive efforts for the transformation of Dinitrogen using transition metal–Dinitrogen complexes as catalysts under mild reaction conditions have been made. However, limited systems have succeeded in the catalytic formation of ammonia. Here we show that newly designed and prepared Dinitrogen-bridged dimolybdenum complexes bearing N-heterocyclic carbene- and phosphine-based PCP-pincer ligands [{Mo(N2)2(PCP)}2(μ-N2)] (1) work as so far the most effective catalysts towards the formation of ammonia from Dinitrogen under ambient reaction conditions, where up to 230 equiv. of ammonia are produced based on the catalyst. DFT calculations on 1 reveal that the PCP-pincer ligand serves as not only a strong σ-donor but also a π-acceptor. These electronic properties are responsible for a solid connection between the molybdenum centre and the pincer ligand, leading to the enhanced catalytic activity for nitrogen fixation. Catalytic nitrogen fixation is a very active research area, given the need to develop mild routes for ammonia production. Here the authors report a PCP-pincer molybdenum complex allowing for highly efficient ammonia generation under ambient conditions.
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interplay between theory and experiment for ammonia synthesis catalyzed by transition metal complexes
ChemInform, 2016Co-Authors: Hiromasa Tanaka, Yoshiaki Nishibayashi, Kazunari YoshizawaAbstract:ConspectusNitrogen fixation is an essential chemical process both biologically and industrially. Since the discovery of the first transition-metal–Dinitrogen complex in 1965, a great deal of effort has been devoted to the development of artificial nitrogen fixation systems that work under mild reaction conditions. However, the transformation of chemically inert Dinitrogen using homogeneous catalysts is still challenging because of the difficulty in breaking the strong triple bond of Dinitrogen, and a very limited number of transition metal complexes have exhibited the catalytic activity for the direct transformation of Dinitrogen into ammonia with low turnover numbers. To develop more effective nitrogen fixation systems, it is necessary to retrieve as much information as possible from the limited successful examples. Computational chemistry will provide valuable insights in the understanding of the reaction mechanisms involving unstable intermediates that are hard to isolate or characterize. We have been ...
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Catalytic transformation of Dinitrogen into ammonia and hydrazine by iron-Dinitrogen complexes bearing pincer ligand
Nature Communications, 2016Co-Authors: Shogo Kuriyama, Kazuya Arashiba, Yuki Matsuo, Kazuyuki Ishii, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Yoshiaki NishibayashiAbstract:Synthesis and reactivity of iron-Dinitrogen complexes have been extensively studied, because the iron atom plays an important role in the industrial and biological nitrogen fixation. As a result, iron-catalyzed reduction of molecular Dinitrogen into ammonia has recently been achieved. Here we show that an iron-Dinitrogen complex bearing an anionic PNP-pincer ligand works as an effective catalyst towards the catalytic nitrogen fixation, where a mixture of ammonia and hydrazine is produced. In the present reaction system, molecular Dinitrogen is catalytically and directly converted into hydrazine by using transition metal-Dinitrogen complexes as catalysts. Because hydrazine is considered as a key intermediate in the nitrogen fixation in nitrogenase, the findings described in this paper provide an opportunity to elucidate the reaction mechanism in nitrogenase.
Hiromasa Tanaka - One of the best experts on this subject based on the ideXlab platform.
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structural characterization of molybdenum Dinitrogen complex as key species toward ammonia formation by dispersive xafs spectroscopy
Physical Chemistry Chemical Physics, 2020Co-Authors: Akira Yamamoto, Kazuya Arashiba, Kazunari Yoshizawa, Yoshiaki Nishibayashi, Hiromasa Tanaka, Shimpei Naniwa, Kazuo Kato, Hisao YoshidaAbstract:The structural characterization of a hardly-isolatable molybdenum–Dinitrogen complex bearing a PNP-type pincer ligand, which is assumed to be a key reactive complex in the stoichiometric transformation of a molybdenum triiodide complex [MoI3(PNP)] into the corresponding molybdenum nitride complex under an atmospheric pressure of Dinitrogen, was carried out by using dispersive XAFS.
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catalytic nitrogen fixation via direct cleavage of nitrogen nitrogen triple bond of molecular Dinitrogen under ambient reaction conditions
Bulletin of the Chemical Society of Japan, 2017Co-Authors: Kazuya Arashiba, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Aya Eizawa, Yoshiaki NishibayashiAbstract:We have now found that molybdenum–iodide complexes bearing a PNP-pincer ligand have a higher catalytic activity than the so far reported molybdenum–Dinitrogen complexes for ammonia formation from nitrogen gas under ambient reaction conditions, up to 830 equiv being produced based on a Dinitrogen-bridged dimolybdenum complex (415 equiv of ammonia based on the molybdenum atom). This remarkable catalytic activity is induced by a novel reaction pathway, where the generation of a Dinitrogen-bridged dimolybdenum–iodide complex is a key point to promote direct cleavage of the nitrogen–nitrogen triple bond of the bridging Dinitrogen ligand in the Mo–N≡N–Mo core.
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remarkable catalytic activity of Dinitrogen bridged dimolybdenum complexes bearing nhc based pcp pincer ligands toward nitrogen fixation
Nature Communications, 2017Co-Authors: Aya Eizawa, Yuki Matsuo, Shogo Kuriyama, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa TanakaAbstract:Intensive efforts for the transformation of Dinitrogen using transition metal–Dinitrogen complexes as catalysts under mild reaction conditions have been made. However, limited systems have succeeded in the catalytic formation of ammonia. Here we show that newly designed and prepared Dinitrogen-bridged dimolybdenum complexes bearing N-heterocyclic carbene- and phosphine-based PCP-pincer ligands [{Mo(N2)2(PCP)}2(μ-N2)] (1) work as so far the most effective catalysts towards the formation of ammonia from Dinitrogen under ambient reaction conditions, where up to 230 equiv. of ammonia are produced based on the catalyst. DFT calculations on 1 reveal that the PCP-pincer ligand serves as not only a strong σ-donor but also a π-acceptor. These electronic properties are responsible for a solid connection between the molybdenum centre and the pincer ligand, leading to the enhanced catalytic activity for nitrogen fixation. Catalytic nitrogen fixation is a very active research area, given the need to develop mild routes for ammonia production. Here the authors report a PCP-pincer molybdenum complex allowing for highly efficient ammonia generation under ambient conditions.
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interplay between theory and experiment for ammonia synthesis catalyzed by transition metal complexes
ChemInform, 2016Co-Authors: Hiromasa Tanaka, Yoshiaki Nishibayashi, Kazunari YoshizawaAbstract:ConspectusNitrogen fixation is an essential chemical process both biologically and industrially. Since the discovery of the first transition-metal–Dinitrogen complex in 1965, a great deal of effort has been devoted to the development of artificial nitrogen fixation systems that work under mild reaction conditions. However, the transformation of chemically inert Dinitrogen using homogeneous catalysts is still challenging because of the difficulty in breaking the strong triple bond of Dinitrogen, and a very limited number of transition metal complexes have exhibited the catalytic activity for the direct transformation of Dinitrogen into ammonia with low turnover numbers. To develop more effective nitrogen fixation systems, it is necessary to retrieve as much information as possible from the limited successful examples. Computational chemistry will provide valuable insights in the understanding of the reaction mechanisms involving unstable intermediates that are hard to isolate or characterize. We have been ...
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Catalytic transformation of Dinitrogen into ammonia and hydrazine by iron-Dinitrogen complexes bearing pincer ligand
Nature Communications, 2016Co-Authors: Shogo Kuriyama, Kazuya Arashiba, Yuki Matsuo, Kazuyuki Ishii, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Yoshiaki NishibayashiAbstract:Synthesis and reactivity of iron-Dinitrogen complexes have been extensively studied, because the iron atom plays an important role in the industrial and biological nitrogen fixation. As a result, iron-catalyzed reduction of molecular Dinitrogen into ammonia has recently been achieved. Here we show that an iron-Dinitrogen complex bearing an anionic PNP-pincer ligand works as an effective catalyst towards the catalytic nitrogen fixation, where a mixture of ammonia and hydrazine is produced. In the present reaction system, molecular Dinitrogen is catalytically and directly converted into hydrazine by using transition metal-Dinitrogen complexes as catalysts. Because hydrazine is considered as a key intermediate in the nitrogen fixation in nitrogenase, the findings described in this paper provide an opportunity to elucidate the reaction mechanism in nitrogenase.
Kazuya Arashiba - One of the best experts on this subject based on the ideXlab platform.
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structural characterization of molybdenum Dinitrogen complex as key species toward ammonia formation by dispersive xafs spectroscopy
Physical Chemistry Chemical Physics, 2020Co-Authors: Akira Yamamoto, Kazuya Arashiba, Kazunari Yoshizawa, Yoshiaki Nishibayashi, Hiromasa Tanaka, Shimpei Naniwa, Kazuo Kato, Hisao YoshidaAbstract:The structural characterization of a hardly-isolatable molybdenum–Dinitrogen complex bearing a PNP-type pincer ligand, which is assumed to be a key reactive complex in the stoichiometric transformation of a molybdenum triiodide complex [MoI3(PNP)] into the corresponding molybdenum nitride complex under an atmospheric pressure of Dinitrogen, was carried out by using dispersive XAFS.
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catalytic nitrogen fixation via direct cleavage of nitrogen nitrogen triple bond of molecular Dinitrogen under ambient reaction conditions
Bulletin of the Chemical Society of Japan, 2017Co-Authors: Kazuya Arashiba, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Aya Eizawa, Yoshiaki NishibayashiAbstract:We have now found that molybdenum–iodide complexes bearing a PNP-pincer ligand have a higher catalytic activity than the so far reported molybdenum–Dinitrogen complexes for ammonia formation from nitrogen gas under ambient reaction conditions, up to 830 equiv being produced based on a Dinitrogen-bridged dimolybdenum complex (415 equiv of ammonia based on the molybdenum atom). This remarkable catalytic activity is induced by a novel reaction pathway, where the generation of a Dinitrogen-bridged dimolybdenum–iodide complex is a key point to promote direct cleavage of the nitrogen–nitrogen triple bond of the bridging Dinitrogen ligand in the Mo–N≡N–Mo core.
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Catalytic transformation of Dinitrogen into ammonia and hydrazine by iron-Dinitrogen complexes bearing pincer ligand
Nature Communications, 2016Co-Authors: Shogo Kuriyama, Kazuya Arashiba, Yuki Matsuo, Kazuyuki Ishii, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Yoshiaki NishibayashiAbstract:Synthesis and reactivity of iron-Dinitrogen complexes have been extensively studied, because the iron atom plays an important role in the industrial and biological nitrogen fixation. As a result, iron-catalyzed reduction of molecular Dinitrogen into ammonia has recently been achieved. Here we show that an iron-Dinitrogen complex bearing an anionic PNP-pincer ligand works as an effective catalyst towards the catalytic nitrogen fixation, where a mixture of ammonia and hydrazine is produced. In the present reaction system, molecular Dinitrogen is catalytically and directly converted into hydrazine by using transition metal-Dinitrogen complexes as catalysts. Because hydrazine is considered as a key intermediate in the nitrogen fixation in nitrogenase, the findings described in this paper provide an opportunity to elucidate the reaction mechanism in nitrogenase.
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catalytic formation of ammonia from molecular Dinitrogen by use of Dinitrogen bridged dimolybdenum Dinitrogen complexes bearing pnp pincer ligands remarkable effect of substituent at pnp pincer ligand
Journal of the American Chemical Society, 2014Co-Authors: Shogo Kuriyama, Kazuya Arashiba, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Nobuaki Kamaru, Yoshiaki NishibayashiAbstract:A series of Dinitrogen-bridged dimolybdenum–Dinitrogen complexes bearing 4-substituted PNP-pincer ligands are synthesized by the reduction of the corresponding molybdenum trichloride complexes under 1 atm of molecular Dinitrogen. In accordance with a theoretical study, the catalytic activity is enhanced by the introduction of an electron-donating group to the pyridine ring of PNP-pincer ligand, and the complex bearing 4-methoxy-substituted PNP-pincer ligands is found to work as the most effective catalyst, where 52 equiv of ammonia are produced based on the catalyst (26 equiv of ammonia based on each molybdenum atom of the catalyst), together with molecular dihydrogen as a side-product. Time profiles for the catalytic reactions indicate that the rates of the formation of ammonia and molecular dihydrogen depend on the nature of the substituent on the PNP-pincer ligand of the complexes. The formation of ammonia and molecular dihydrogen is complementary in the reaction system.
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unique behaviour of Dinitrogen bridged dimolybdenum complexes bearing pincer ligand towards catalytic formation of ammonia
Nature Communications, 2014Co-Authors: Kazuya Arashiba, Shogo Kuriyama, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Akira Sasada, Yoshiaki NishibayashiAbstract:It is vital to design effective nitrogen fixation systems that operate under mild conditions, and to this end we recently reported an example of the catalytic formation of ammonia using a Dinitrogen-bridged dimolybdenum complex bearing a pincer ligand, where up to twenty three equivalents of ammonia were produced based on the catalyst. Here we study the origin of the catalytic behaviour of the Dinitrogen-bridged dimolybdenum complex bearing the pincer ligand with density functional theory calculations, based on stoichiometric and catalytic formation of ammonia from molecular Dinitrogen under ambient conditions. Comparison of di- and mono-molybdenum systems shows that the Dinitrogen-bridged dimolybdenum core structure plays a critical role in the protonation of the coordinated molecular Dinitrogen in the catalytic cycle.
Shogo Kuriyama - One of the best experts on this subject based on the ideXlab platform.
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remarkable catalytic activity of Dinitrogen bridged dimolybdenum complexes bearing nhc based pcp pincer ligands toward nitrogen fixation
Nature Communications, 2017Co-Authors: Aya Eizawa, Yuki Matsuo, Shogo Kuriyama, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa TanakaAbstract:Intensive efforts for the transformation of Dinitrogen using transition metal–Dinitrogen complexes as catalysts under mild reaction conditions have been made. However, limited systems have succeeded in the catalytic formation of ammonia. Here we show that newly designed and prepared Dinitrogen-bridged dimolybdenum complexes bearing N-heterocyclic carbene- and phosphine-based PCP-pincer ligands [{Mo(N2)2(PCP)}2(μ-N2)] (1) work as so far the most effective catalysts towards the formation of ammonia from Dinitrogen under ambient reaction conditions, where up to 230 equiv. of ammonia are produced based on the catalyst. DFT calculations on 1 reveal that the PCP-pincer ligand serves as not only a strong σ-donor but also a π-acceptor. These electronic properties are responsible for a solid connection between the molybdenum centre and the pincer ligand, leading to the enhanced catalytic activity for nitrogen fixation. Catalytic nitrogen fixation is a very active research area, given the need to develop mild routes for ammonia production. Here the authors report a PCP-pincer molybdenum complex allowing for highly efficient ammonia generation under ambient conditions.
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Catalytic transformation of Dinitrogen into ammonia and hydrazine by iron-Dinitrogen complexes bearing pincer ligand
Nature Communications, 2016Co-Authors: Shogo Kuriyama, Kazuya Arashiba, Yuki Matsuo, Kazuyuki Ishii, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Yoshiaki NishibayashiAbstract:Synthesis and reactivity of iron-Dinitrogen complexes have been extensively studied, because the iron atom plays an important role in the industrial and biological nitrogen fixation. As a result, iron-catalyzed reduction of molecular Dinitrogen into ammonia has recently been achieved. Here we show that an iron-Dinitrogen complex bearing an anionic PNP-pincer ligand works as an effective catalyst towards the catalytic nitrogen fixation, where a mixture of ammonia and hydrazine is produced. In the present reaction system, molecular Dinitrogen is catalytically and directly converted into hydrazine by using transition metal-Dinitrogen complexes as catalysts. Because hydrazine is considered as a key intermediate in the nitrogen fixation in nitrogenase, the findings described in this paper provide an opportunity to elucidate the reaction mechanism in nitrogenase.
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catalytic formation of ammonia from molecular Dinitrogen by use of Dinitrogen bridged dimolybdenum Dinitrogen complexes bearing pnp pincer ligands remarkable effect of substituent at pnp pincer ligand
Journal of the American Chemical Society, 2014Co-Authors: Shogo Kuriyama, Kazuya Arashiba, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Nobuaki Kamaru, Yoshiaki NishibayashiAbstract:A series of Dinitrogen-bridged dimolybdenum–Dinitrogen complexes bearing 4-substituted PNP-pincer ligands are synthesized by the reduction of the corresponding molybdenum trichloride complexes under 1 atm of molecular Dinitrogen. In accordance with a theoretical study, the catalytic activity is enhanced by the introduction of an electron-donating group to the pyridine ring of PNP-pincer ligand, and the complex bearing 4-methoxy-substituted PNP-pincer ligands is found to work as the most effective catalyst, where 52 equiv of ammonia are produced based on the catalyst (26 equiv of ammonia based on each molybdenum atom of the catalyst), together with molecular dihydrogen as a side-product. Time profiles for the catalytic reactions indicate that the rates of the formation of ammonia and molecular dihydrogen depend on the nature of the substituent on the PNP-pincer ligand of the complexes. The formation of ammonia and molecular dihydrogen is complementary in the reaction system.
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unique behaviour of Dinitrogen bridged dimolybdenum complexes bearing pincer ligand towards catalytic formation of ammonia
Nature Communications, 2014Co-Authors: Kazuya Arashiba, Shogo Kuriyama, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Akira Sasada, Yoshiaki NishibayashiAbstract:It is vital to design effective nitrogen fixation systems that operate under mild conditions, and to this end we recently reported an example of the catalytic formation of ammonia using a Dinitrogen-bridged dimolybdenum complex bearing a pincer ligand, where up to twenty three equivalents of ammonia were produced based on the catalyst. Here we study the origin of the catalytic behaviour of the Dinitrogen-bridged dimolybdenum complex bearing the pincer ligand with density functional theory calculations, based on stoichiometric and catalytic formation of ammonia from molecular Dinitrogen under ambient conditions. Comparison of di- and mono-molybdenum systems shows that the Dinitrogen-bridged dimolybdenum core structure plays a critical role in the protonation of the coordinated molecular Dinitrogen in the catalytic cycle.
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Catalytic Formation of Ammonia from Molecular Dinitrogen by Use of Dinitrogen-Bridged Dimolybdenum–Dinitrogen Complexes Bearing PNP-Pincer Ligands: Remarkable Effect of Substituent at PNP-Pincer Ligand
2014Co-Authors: Shogo Kuriyama, Kazuya Arashiba, Kazunari Nakajima, Kazunari Yoshizawa, Hiromasa Tanaka, Nobuaki Kamaru, Yoshiaki NishibayashiAbstract:A series of Dinitrogen-bridged dimolybdenum–Dinitrogen complexes bearing 4-substituted PNP-pincer ligands are synthesized by the reduction of the corresponding molybdenum trichloride complexes under 1 atm of molecular Dinitrogen. In accordance with a theoretical study, the catalytic activity is enhanced by the introduction of an electron-donating group to the pyridine ring of PNP-pincer ligand, and the complex bearing 4-methoxy-substituted PNP-pincer ligands is found to work as the most effective catalyst, where 52 equiv of ammonia are produced based on the catalyst (26 equiv of ammonia based on each molybdenum atom of the catalyst), together with molecular dihydrogen as a side-product. Time profiles for the catalytic reactions indicate that the rates of the formation of ammonia and molecular dihydrogen depend on the nature of the substituent on the PNP-pincer ligand of the complexes. The formation of ammonia and molecular dihydrogen is complementary in the reaction system