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Yoshiaki Nishibayashi - One of the best experts on this subject based on the ideXlab platform.
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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, Aya Eizawa, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, Shogo Kuriyama, 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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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developing more sustainable processes for ammonia synthesis
Coordination Chemistry Reviews, 2013Co-Authors: Yoshiaki Tanabe, Yoshiaki NishibayashiAbstract:Abstract This paper describes a recent advance on the conversion of molecular dinitrogen into ammonia or ammonia equivalent, silylamine, by using transition metal–dinitrogen complexes. Two effective systems for the catalytic transformation of molecular dinitrogen under ambient reaction conditions have been achieved by the use of molybdenum and iron complexes as catalysts. The former system employs a molybdenum–dinitrogen complex bearing two ferrocenyl diphosphines or an iron complex such as iron carbonyl or substituted ferrocene as a catalyst to afford up to 226 equiv of silylamine based on the catalyst. The latter system employs a dinitrogen-bridged Dimolybdenum complex bearing two PNP-type pincer ligands as a catalyst to afford up to 23 equiv of ammonia based on the catalyst. Both systems provide a new aspect in the development of novel nitrogen fixation under mild reaction conditions.
Kazuya Arashiba - One of the best experts on this subject based on the ideXlab platform.
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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, Aya Eizawa, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, Shogo Kuriyama, 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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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Synthesis and Catalytic Activity of Molybdenum–Dinitrogen Complexes Bearing Unsymmetric PNP-Type Pincer Ligands
2012Co-Authors: Eriko Kinoshita, Kazuya Arashiba, Shogo Kuriyama, Yoshihiro Miyake, Ryuji Shimazaki, Haruyuki Nakanishi, Yoshiaki NishibayashiAbstract:Novel dinitrogen-bridged Dimolybdenum complexes bearing unsymmetric PNP-type pincer ligands are prepared and characterized by X-ray analysis. A molybdenum–dinitrogen complex bearing 2-(di-1-adamantylphosphino)methyl-6-(di-tert-butylphosphino)methylpyridine has been found to work as an effective catalyst toward the formation of ammonia from molecular dinitrogen under ambient conditions
Hiromasa Tanaka - One of the best experts on this subject based on the ideXlab platform.
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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, Aya Eizawa, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, Shogo Kuriyama, 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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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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, Aya Eizawa, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, Shogo Kuriyama, 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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 Nakajima - One of the best experts on this subject based on the ideXlab platform.
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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, Aya Eizawa, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, Shogo Kuriyama, 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, Hiromasa Tanaka, Kazunari Nakajima, Kazunari Yoshizawa, 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