Nitrogen fixation catalyzed by ferrocene-substituted dinitrogen-bridged dimolybdenum–dinitrogen complexes: unique behavior of ferrocene moiety as redox active site
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
摘要:
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.
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
Mechanisms of Electrochemical N<sub>2</sub> Splitting by a Molybdenum Pincer Complex
作者:Quinton J. Bruch、Santanu Malakar、Alan S. Goldman、Alexander J. M. Miller
DOI:10.1021/acs.inorgchem.1c03698
日期:2022.1.31
providing a foundation for a detailed mechanisticstudy of electrode-driven formation of the nitride complex (pyPNP)Mo(N)Br. Electrochemical kinetic analysis, optical and vibrational spectroelectrochemical monitoring, and computational studies point to two concurrent reaction pathways: In the reaction–diffusion layer near the electrode surface, the molybdenum(III) precursor is reduced by 2e– and generates
三齿钳配体负载的钼配合物是使用化学还原剂固定二氮的特殊催化剂,但对其电化学还原二氮的前景知之甚少。钼 (III) 钳形配合物 ( py PNP)MoBr 3 ( py PNP = 2,6-bis( t Bu 2 PCH 2 )-C 5 H 3 N))对电化学 N 2结合和分裂的可行性为在这项工作中建立,为电极驱动的氮化物复合物(pyPNP)Mo(N)Br。电化学动力学分析、光学和振动光谱电化学监测以及计算研究指出了两条同时发生的反应途径:在电极表面附近的反应-扩散层中,钼 (III) 前体被 2e 还原-并生成双金属钼 (I) Mo 2 (μ-N 2 ) 能断裂 N-N 键的物质;在远离电极表面的本体溶液中,过度还原的钼(0)物质通过歧化作用发生化学氧化还原反应,生成相同的能够分解N 2的双金属钼(I)物质。比例化反应揭示了二钼(0)络合物反式,反式-[(py PNP)Mo(N 2 ) 2
Synthesis and Protonation of Molybdenum– and Tungsten–Dinitrogen Complexes Bearing PNP-Type Pincer Ligands
Novel molybdenum- and tungsten dinitrogen complexes bearing PNP-type pincer ligands are prepared and characterized by X-ray analysis. Reactions of these molybdenum- and tungsten-dinitrogen complexes with an excess amount of sulfuric acid in THF at room temperature afford ammonia and hydrazine in good yields.
Preparation and reactivity of a dinitrogen-bridged dimolybdenum-tetrachloride complex
A dinitrogen-bridged dimolybdenum-tetrachloride complex is prepared and reduced with Super-Hydride (LiBHEt3) to afford the corresponding dimolybdenum-dinitrogen complex together with the formation of molecular dihydrogen. This reaction proceeds via the ligand exchange of the coordinateddihydrogen generated in situ with molecular dinitrogen.
Nitrogen fixation catalyzed by ferrocene-substituted dinitrogen-bridged dimolybdenum–dinitrogen complexes: unique behavior of ferrocene moiety as redox active site
Mo–N2complex bearing ferrocenes as redox-active units efficiently catalyses the formation of ammonia from molecular dinitrogen under ambient conditions.