Development of dinitrogen activation and ammonia synthesis by high-valence metal complexes

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K05734
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Inorganic chemistry
• Research Institution: Aichi Institute of Technology
• Principal Investigator: Kajita Yuji 愛知工業大学, 工学部, 准教授 (60397495)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 窒素固定 / 窒素錯体 / 窒素活性化 / バナジウム / クロム / 二核錯体

Outline of Final Research Achievements

In this study, we succeeded to synthesize high-valent vanadium-, and chromium-dinitrogen complexes. When vanadium-dinitrogen complexes reacted with H+ in the presence of a reductant, only ammonia has formed, however, only hydrazine or hydrazine and ammonia have formed in case of chromium-dinitrogen complexes. We could not synthesize a nitride complex from the N-N bond cleavage of bridging N2 ligand in their dinitrogen complexes, however, we found that the yield of ammonia increases with preventing the decomposition of a dinitrogen complex in redox reactions. Particularly, we succeeded to improve the yield of ammonia to about 350% in case of vanadium-dinitrogen complex with 4-a methylbenzyl group. And when a vanadium-dinitrogen complex reacts with sodium or potassium, a alkali metal ion adduct forms without cleavage of a M-NN2 or a N-N bond, however, when using a chromium-dinitrogen complex, form a alkali metal ion adduct with cleavage of Cr-NN2 bond.

Free Research Field

錯体化学

Academic Significance and Societal Importance of the Research Achievements

本研究において、高原子価窒素錯体の合成に成功したことは、窒素錯体の前駆体に高いポテンシャルを与えなくても遷移金属錯体上で窒素を活性化させることが可能であることを示している。このことは人工窒素固定法では必ずしも高温高圧を必要としないことを示しており、学術的意義は大変高い。また、窒素錯体を還元剤と反応させることによって、窒素配位子と中心金属の結合を優先的に切断できることは、窒素の選択的回収や除去に利用することができ、社会的意義も大きい。