Dinitrogen complexation and reduction at low-valent calcium.

Rösch, B; Gentner, T X; Langer, J; Färber, C; Eyselein, J; Zhao, L; Ding, C; Frenking, G et al. · Science · 2021

basic_science · Level V

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Abstract

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