Synthesis and Characterization of a New Ternary ImideLi₂Ca(NH)₂

The ternary imide Li₂Ca(NH)₂ was successfully synthesized by dehydrogenating a mixture of LiNH₂ and CaH₂ at a molar ratio of 2:1 in a stream of purified argon at 300 °C. A powder X-ray diffraction measurement revealed that Li₂Ca(NH)₂ was of the trigonal anti-La₂O₃ structure (space group P3̄m1) with lattice constants of a = 3.5664(3)Å and c = 5.9540(8) Å. Ca occupied the 1b site (0, 0, 1/2), Li occupied the 2d site (1/3, 2/3, 0.8841(22)), and N occupied the 2d site (1/3, 2/3, 0.2565(15)). Nuclear magnetic resonance and X-ray absorption fine structure analyses demonstrated that each Li ion was coordinated with four imide ions and each Ca ion was coordinated with six imide ions.