Room-temperature H2 splitting and N2-hydrogenation induced by a neutral Lu(II) complex

The direct splitting of the H2 and N2 molecules are challenging reactions that are 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.