Ammonia synthesis at room temperature and atmospheric pressure from N${}_2$. A boron-radical approach

Ammonia, NH${}_3$, is an essential molecule, being part of fertilizers. It is currently synthesized via the Haber-Bosch process, from the very stable dinitrogen molecule, N${}_2$ and dihydrogen, H${}_2$. This process requires high temperatures and pressures, thereby generating ca 1.6 % of the global CO${}_2$ emissions. Alternative strategies are needed to realize the functionalization of N${}_2$ to NH${}_3$ under mild conditions. Here, we show that boron-centered radicals provide a means of activating N${}_2$ at room temperature and atmospheric pressure whilst allowing a radical process to occur, leading to the production of borylamines. Subsequent hydrolysis released NH${}_4$${}^{+}$, the acidic form of NH${}_3$. EPR spectroscopy supported the intermediacy of radicals in the process, corroborated by DFT calculations, which rationalized the mechanism of the N${}_2$ functionalization by R${}_2$B radicals. (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH)