Rapid Microwave Synthesis, Characterization and Reactivity of Lithium Nitride Hydride, Li4NH

Lithium nitride hydride, Li4NH, was synthesised from lithium nitride and lithium hydride over minute timescales, using microwave synthesis methods in the solid state for the first time. The structure of the microwave-synthesised powders was confirmed by powder X-ray diffraction [tetragonal space group I41/a; a = 4.8864(1) Å, c = 9.9183(2) Å] and the nitride hydride reacts with moist air under ambient conditions to produce lithium hydroxide and subsequently lithium carbonate. Li4NH undergoes no dehydrogenation or decomposition [under Ar(g)] below 773 K. A tetragonal–cubic phase transition, however, occurs for the compound at ca. 770 K. The new high temperature (HT) phase adopts an anti-fluorite structure (space group Fm 3̅ m; a = 4.9462(3) Å) with N3− and H− ions disordered on the 4a sites. Thermal treatment of Li4NH under nitrogen yields a stoichiometric mixture of lithium nitride and lithium imide (Li3N and Li2NH respectively)

Kristallstrukturbestimmung an einer Strontium-hydrid-imid-nitrid-Phase – Sr2(H)N/SrNH\mathrm{Sr_2(H)N/SrNH} bzw. Sr2(D)N/SrND\mathrm{Sr_2(D)N/SrND} – mit Röntgen-, Neutronen- und Synchrotron-Strahlung

Strontium reacts with nitrogen and hydrogen or deuterium under defined conditions to form a phase in which hydride, imide and nitride ions are present side by side.Sr is evaporated at 1000 ° C. The reaction with N 2 and H 2 or D 2 (p (N 2 ) = p (H 2 / D 2 ) = 50 mbar) takes place in the gas phase. The product crystallizes as orange-yellow or black crystal needles at 800 ° C.Neither from X-ray single crystal nor from X-ray or neutron diffraction powder data could the crystal structure be clearly determined. Only a high-resolution diffraction experiment with synchrotron radiation at the powder gave decisive indications for a structural model:Fractions of reflections can only be explained with a model in R 3 m with a = 3,870 (1) Å and c = 18,958 (3) Å. Additional reflections show that, in addition to Sr 2 (H), there are N regions with SrNH as the second phase. The refinement of neutron diffraction data (measurements at 2 K, 10 K, 300 K and 505 K) with a two-phase model Sr 2 (D) N / SrND leads to a meaningful result: in a slightly distorted cubic dense arrangement of Sr atoms occupy layers in Domains Hydride and nitride ions or imide ions Octahedral gaps completely and ordered to one third each

Synthesis and structural characterization of a new alkaline earth imide: MgCa(NH)2

10.1002/ejic.200600492European Journal of Inorganic Chemistry214368-4373EJIC