Molecular nitrogen (N2) is abundant in the atmosphere and nitrogen, found in many biomolecules, is an essential element of life. The Haber–Bosch process, developed over 100 years ago, requires relatively harsh conditions to activate N2 on the iron surface and generate ammonia for use as fertilizer or to produce other chemicals, leading to consumption of more than 2% of the world’s annual energy supply. Thus, developing approaches for N2 activation under mild conditions is particularly important and urgent. Here we demonstrate that a metal-free N2 activation could be favorable both thermodynamically and kinetically (with an activation energy as low as 9.1 kcal mol-1) by a carbon-boron formal frustrated Lewis pair, which is supported by high-level coupled cluster calculations. Mechanistic studies reveal that aromaticity plays a crucial role in stabilizing both the transition state and the product. Our findings highlight the importance of a combination of N-heterocyclic carbene with a methyleneborane unit in metal-free N2 activation, providing conceptual guidance for experimental realization.

https://onlinelibrary.wiley.com/doi/abs/10.1002/asia.201900010