Ammonia Synthesis at Room Temperature and Atmospheric Pressure from N2 : A Boron-Radical Approach

Angew Chem Int Ed Engl. 2023 Jan 16;62(3):e202209102. doi: 10.1002/anie.202209102. Epub 2022 Dec 13.

Abstract

Ammonia, NH3 , is an essential molecule, being part of fertilizers. It is currently synthesized via the Haber-Bosch process, from the very stable dinitrogen molecule, N2 and dihydrogen, H2 . This process requires high temperatures and pressures, thereby generating ca 1.6 % of the global CO2 emissions. Alternative strategies are needed to realize the functionalization of N2 to NH3 under mild conditions. Here, we show that boron-centered radicals provide a means of activating N2 at room temperature and atmospheric pressure whilst allowing a radical process to occur, leading to the production of borylamines. Subsequent hydrolysis released NH4 + , the acidic form of NH3 . EPR spectroscopy supported the intermediacy of radicals in the process, corroborated by DFT calculations, which rationalized the mechanism of the N2 functionalization by R2 B radicals.

Keywords: Boron Radical; Density-Functional Calculations; N2 Fixation; Reaction Mechanims; Reduction.