Molybdenum-Catalyzed Ammonia Synthesis by Using Zero-Valent Metal Powder with Alcohols or Water.

We have recently achieved a highly effective ammonia formation from dinitrogen using samarium diiodide and water under ambient reaction conditions. However, further research is needed to establish a carbon-free green ammonia production route without carbon dioxide emissions. In this study, we have developed a novel molybdenum-catalyzed nitrogen fixation method using a combination of zero-valent metal powders as reductants and alcohols or H2O as a proton source under ambient reaction conditions. In this reaction system, samarium compounds serve as crucial electron mediators for the molybdenum complexes. Remarkably, the combination of zinc powder and water in the presence of samarium triiodide facilitates highly selective ammonia production over dihydrogen under ambient reaction conditions, yielding up to 900 equiv of ammonia per Mo atom in the catalyst. Intriguingly, using magnesium powder, known for its potent reducing capability, reduces the requisite amount of samarium compounds to catalytic levels. We believe that the novel insights gained from this reaction system represent a substantial step toward achieving green ammonia production.