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

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Direct conversion of dinitrogen (N 2 ) into organic compounds, not through ammonia (NH 3 ), 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 N 2 and carbon-based electrophiles. The cycle includes three main steps: (i) reduction of a halogen-bridged discandium complex under N 2 leading to a (N 2 ) 3– -bridged discandium complex via a (N 2 ) 2– intermediate; (ii) treatment of the (N 2 ) 3– complex with methyl triflate (MeOTf), affording a (N 2 Me 2 ) 2– -bridged discandium complex; and (iii) further reaction of the (N 2 Me 2 ) 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 (N 2 Me 2 ) 2– –scandium complex was observed. Most notably, this is the first example of rare-earth metal-promoted direct conversion of N 2 to organic compounds; the formation of C–N bonds by the reaction of these (N 2 ) 3– and (N 2 Me 2 ) 2– complexes with electrophiles represents the first case among all N 2 –metal complexes reported.