Synthesis and Structure of a Mononuclear η²‐Hydrazine Complex by Protonation of an [N₂H₂]²⁻ Complex

The synthetic route to the η2-hydrazine–samarium complex 1 parallels protonations which were postulated for the N2 fixation in biological systems. Thus 1 was formed by a double H +-transfer onto the bridging (N2H2)2− ligand of the dinuclear complex 2. The hydrazine ligand is bound firmly to the Sm center and cannot be removed by either vacuum or recrystallization in potentially coordinating solvents.