Chain‐Type Lithium Rare‐Earth Nitridosilicates – Li₅Ln₅Si₄N₁₂ with Ln = La, Ce

Abstract

Abstract The quaternary lithium rare‐earth nitridosilicates Li 5 Ln 5 Si 4 N 12 with Ln = La, Ce were synthesized at moderate temperatures below 900 °C in closed tantalum ampoules employing liquid lithium as a flux. Thereby, nitridosilicate substructures with a low degree of condensation were obtained. The air and moisture sensitive title compounds are the first representatives of quaternary lithium rare‐earth nitridosilicates and crystallize in space group P $\bar {4}$ b 2 [Li 5 La 5 Si 4 N 12 : a = 1104.28(16), c = 557.30(11) pm, Z = 2, R 1 = 0.0498, 873 data, 56 parameters; Li 5 Ce 5 Si 4 N 12 : a = 1097.78(16), c = 551.43(11) pm, Z = 2, R 1 = 0.0334, 748 data, 56 parameters]. The nitridosilicate substructure consists of infinite nonbranched zweier single‐chains of vertex sharing SiN 4 tetrahedra running parallel to [001]. The chains exhibit a stretching factor f S = 0.981 for La and 0.977 for Ce, respectively. The two crystallographically independent Li + sites are each coordinated by four nitrogen atoms. Lattice energy calculations (MAPLE) and EDX measurements confirmed the electrostatic bonding interactions and the chemical compositions. For the La containing compound 7 Li solid‐state MAS NMR investigations are reported.