Scandium-Promoted Direct Conversion of Dinitrogen into Hydrazine Derivatives via N–C Bond Formation

Direct conversion of dinitrogen (N₂) into organic compounds, not through ammonia (NH₃), is of great significance both fundamentally and practically. Here we report a highly efficient scandium-mediated synthetic cycle affording hydrazine derivatives (RMeN-NMeR') directly from N₂ and carbon-based electrophiles. The cycle includes three main steps: (i) reduction of a halogen-bridged discandium complex under N₂ leading to a (N₂)^3--bridged discandium complex via a (N₂)^2- intermediate; (ii) treatment of the (N₂)^3- complex with methyl triflate (MeOTf), affording a (N₂Me₂)^2--bridged discandium complex; and (iii) further reaction of the (N₂Me₂)^2- complex with the carbon-based electrophile, producing the hydrazine derivative and regenerating the halide precursor. Furthermore, insertion of a CO molecule into one Sc-N bond in the (N₂Me₂)^2--scandium complex was observed. Most notably, this is the first example of rare-earth metal-promoted direct conversion of N₂ to organic compounds; the formation of C-N bonds by the reaction of these (N₂)^3- and (N₂Me₂)^2- complexes with electrophiles represents the first case among all N₂-metal complexes reported.