Mechanochemical transformations in NaNH 2-MgH 2 mixtures

Abstract

Mechanochemical transformations occurring during ball milling of sodium amide (NaNH 2) with magnesium hydride (MgH 2) taken in 2:3 and 2:1 molar ratios have been investigated using X-ray powder diffraction (XRD) and solid-state nuclear magnetic resonance (SSNMR) techniques. For the 2NaNH 2–3MgH 2 system the mechanochemical reaction proceeds via the formation of MgNH as an intermediate, whereas magnesium nitride (Mg 3N 2), sodium hydride (NaH) and hydrogen (∼5 wt%) form as the final products. The overall solid state reaction for this system is 2NaNH 2 + 3MgH 2 → Mg 3N 2 + 2NaH + 4H 2. However, the mechanochemical transformation of the 2NaNH 2–MgH 2 system proceeds through the reaction: 2NaNH 2 + MgH 2 → Mg(NH 2) 2 + 2NaH, without any hydrogen release. Comparison of the mechanochemical transformations with the previously studied thermochemical transformations reveals that the two approaches lead to the same final products via different reaction pathways.