Abstract Initially, the quaternary nitride iodide LiLa4N2I7 was synthesized at 600 °C by a partial metathesis reaction of lithium nitride (Li3N) and lanthanum triiodide (LaI3) within 7 days. Single-phase samples were obtained through annealing of the corresponding binary compounds (LiI, LaN and LaI3) for 20 days overall (4 days at 600 °C prior to 16 days at 500 °C). The title compound crystallizes in the orthorhombic space group Pnma with four formula units per unit cell (a = 1374.17(9), b = 1213.45(8), c = 1079.91(7) pm at 100 K). The dominating structural features are trans-edge shared [NLa4]9+ tetrahedra building up { [ NLa 4 / 2 e ] 3 + } ∞ 1 chains running along [010]. The linkage of these chains via iodide anions leads to a three-dimensional framework, which embeds isolated trigonal bipyramids [LiI4+1]4– with one long besides four short Li+–I– contacts. Infrared spectra of crystalline samples show four main bands between 300 and 600 cm−1, which can probably be assigned as vibrational modes of the condensed [NLa4]9+ tetrahedra. 7Li-MAS NMR spectroscopy reveals a different coordination sphere of Li+ in rocksalt-type LiI than in LiLa4N2I7, but no significant lithium-cation mobility.

中文翻译：

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LiLa4N2I7 作为镧系元素的第一种含锂氮化物卤化物：合成、晶体结构和光谱表征

摘要 最初，通过氮化锂 (Li3N) 和三碘化镧 (LaI3) 在 7 天内的部分复分解反应，在 600 °C 下合成了四元氮化物碘化物 LiLa4N2I7。通过将相应的二元化合物（LiI、LaN 和 LaI3）退火总共 20 天（600°C 下 4 天，然后 500°C 下 16 天）获得单相样品。标题化合物在正交空间群 Pnma 中结晶，每个晶胞有四个分子式单元（a = 1374.17(9), b = 1213.45(8), c = 1079.91(7) pm at 100 K）。主要的结构特征是跨边共享 [NLa4]9+ 四面体构建 { [ NLa 4 / 2 e ] 3 + } ∞ 1 链沿 [010] 运行。这些链通过碘阴离子连接形成一个三维框架，它嵌入了孤立的三角双锥体 [LiI4+1]4–，除了四个短的 Li+–I– 触点外，还有一个长触点。晶体样品的红外光谱显示了 300 到 600 cm-1 之间的四个主要带，这可能被指定为凝聚的 [NLa4]9+ 四面体的振动模式。7Li-MAS NMR 光谱揭示了岩盐型 LiI 中 Li+ 的配位球与 LiLa4N2I7 不同，但没有显着的锂阳离子迁移率。