Catalytic nitrogen fixation using visible light energy

Abstract

The synthesis of ammonia from atmospheric dinitrogen, nitrogen fixation, is one of the essential reactions for human beings. Because the current industrial nitrogen fixation depends on dihydrogen produced from fossil fuels as raw material, the development of a nitrogen fixation reaction that relies on the energy provided by renewable energy, such as visible light, is an important research goal from the viewpoint of sustainable chemistry. Herein, we establish an iridium- and molybdenum-catalysed process for synthesizing ammonia from dinitrogen under ambient reaction conditions and visible light irradiation. In this reaction system, iridium complexes and molybdenum triiodide complexes bearing N-heterocyclic carbene-based pincer ligands act as cooperative catalysts to activate 9,10-dihydroacridine and dinitrogen, respectively. The reaction of dinitrogen with 9,10-dihydroacridine is not thermodynamically favoured, and it only takes place under visible light irradiation. Therefore, the described reaction system is one that affords visible light energy–driven ammonia formation from dinitrogen catalytically.

Catalytic production of ammonia from dinitrogen employing molybdenum complexes bearing N-heterocyclic carbene-based PCP-type pincer ligands

“…As described in here, we consider that the use of the BDFE(N-H) values of key reactive intermediates, such as molybdenum-imide, molybdenum-amide and molybdenum-ammine complexes estimated by DFT calculations provides a suitable and reliable predicting method to develop more effective catalysts under ambient reaction conditions. The catalysts successfully developed will be applied not only to the catalytic nitrogen fixation driven by visible light 62 and electrochemical energy, but also to the catalytic formation of nitrogen-containing organic compounds directly from nitrogen gas under mild reaction conditions 63 . We believe that these findings can contribute to the development of an environmentally friendly next-generation nitrogen-fixation system in the near future.…”

Advancing electrocatalytic nitrogen fixation: insights from molecular systems

“…While such an approach has yet to be reported for N 2 R, a pair of recent studies, including one from our laboratory 57 and also a highly related study published very soon thereafter by Nishibayashi and coworkers, 58 have demonstrated photocatalytic N 2 reduction by well-defined complexes for the first time, using molybdenum N 2 R catalysts (of the type originally reported by Nishibayashi and coworkers for thermally driven N 2 R) partnered with photoactive organic hydride and/or H-atom donors. While notably not required for the system that we reported, 57 an iridium photoredox catalyst facilitates the overall catalysis.…”

Light‐Driven Dinitrogen Activation with Transition Metal Complexes: Mechanisms and Applications†

“…studied an iridium‐ and molybdenum‐catalyzed process for synthesizing ammonia from dinitrogen under ambient reaction conditions and visible light irradiation (Scheme 10). [ 63 ] In this reaction system, iridium complexes and molybdenum triiodide complexes bearing N ‐heterocyclic carbene‐ based pincer ligands act as cooperative catalysts to activate 9,10‐dihydroacridine 33 and dinitrogen, respectively. It should be noted that the reaction of dinitrogen with 33 is not thermodynamically favored, and it only takes place under visible light irradiation.…”