Dinitrogen cleavage and functionalization by carbon monoxide promoted by a hafnium complex

Molecular nitrogen (N₂) and carbon monoxide (CO) have the two strongest bonds in chemistry and present significant challenges in developing new transformations that exploit these two abundant feedstocks. At the core of this objective is the discovery of transition-metal compounds that promote the six-electron reductive cleavage of N₂ at ambient temperature and pressure and also promote new nitrogen-element bond formation. Here we show that an organometallic hafnium compound induces N₂ cleavage on the addition of CO, with a simultaneous assembly of new nitrogen-carbon and carbon-carbon bonds. Subsequent addition of a weak acid liberates oxamide, which demonstrates that an important agrochemical can be synthesized directly from N₂ and CO. These studies introduce an alternative paradigm for N ₂ cleavage and functionalization in which the six-electron reductive cleavage is promoted by both the transition metal and the incoming ligand, CO, used for the new bond formations.