Boron Radical Route to Green Nitrogen: Mechanistic Elucidation and Closing the Synthetic Cycle

Objective

Dinitrogen (N2) is an essential resource for life, agriculture, pharmaceuticals, and materials science, yet its inertness, due to high bond dissociation energy (941 kJ/mol) and a large HOMO-LUMO gap (10.8 eV), makes activation and conversion a major scientific challenge. The energy-intensive Haber-Bosch process, which supports global agriculture, consumes 1-2% of world energy and contributes significantly to CO2 emissions, highlighting the urgent need for sustainable alternatives. Inspired by nitrogenases, recent advances have expanded nitrogen fixation beyond transition metals to main-group elements. A paradigm shift occurred in 2018 with the first boron-based molecular activation of N2, and more recently, the host group achieved metal-free, radical-mediated conversion of N2 to borylamines under mild conditions. However, key mechanistic aspects remain unresolved: radical intermediates are unisolated, uncharacterized, and poorly understood beyond computational predictions. This MSCA project aims to address these gaps by elucidating the mechanism of boron-radical-mediated N2 activation. We will design novel Lewis acids and radical capture agents to isolate and characterize key intermediates such as [R2B-N2]• and [(R2B)2N]• using multimodal analysis (XRD, NMR, EPR, UV-vis, and DFT). Furthermore, the project will demonstrate the release of green nitrogen products (NH₃ and organonitrogens) via electrophilic functionalization and establish a closed synthetic cycle, contributing to sustainable chemistry aligned with EU Critical Raw Materials priorities. By combining fundamental insight with applied goals, this research pioneers a sustainable pathway for nitrogen fixation beyond the Haber-Bosch process.