Room-Temperature H₂ Splitting and N₂-Hydrogenation Induced by a Neutral Lu^II Complex

The direct splitting of H₂ and N₂ molecules is a challenging reaction that is closely related to the Haber-Bosch ammonia synthesis process. Until now, such reactivity has never been observed in the case of molecular lanthanide species. Here, we show that careful selection of the ligand scaffold allows the isolation and characterization of a kinetically stable but highly reactive Lu^II complex. This divalent lanthanide species enables direct H₂ splitting at room temperature, an unknown reactivity in lanthanide chemistry, which has been fully corroborated by DFT calculations. In addition, the Lu^II complex readily binds N₂, leading to an end-on coordinated diazenido (N₂)^2- lanthanide complex. The latter can be hydrogenated under very smooth conditions (ca. 1.2 bar H₂, ambient temperature) to form a unique Lu^III-NH₂ complex. Direct N₂ hydrogenation and cleavage are thus accessible using low-valent molecular rare-earth metal complexes.