Dinitrogen complexation and reduction at low-valent calcium

Here we report that attempted preparation of low-valent CaI complexes in the form of LCa-CaL (where L is a bulky β-diketiminate ligand) under dinitrogen (N₂) atmosphere led to isolation of LCa(N₂)CaL, which was characterized crystallographically. The N₂ ²- anion in this complex reacted in most cases as a very potent two-electron donor. Therefore, LCa(N₂)CaL acts as a synthon for the low-valent CaI complex LCa-CaL, which was the target of our studies. The N₂ ²- anion could also be protonated to diazene (N₂H₂) that disproportionated to hydrazine and N₂ The role of Ca d orbitals for N₂ activation is discussed.