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

The quaternary lithium rare‐earth nitridosilicates Li5Ln5Si4N12 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 P4̄ b2 [Li5La5Si4N12: a = 1104.28(16), c = 557.30(11) pm, Z = 2, R1 = 0.0498, 873 data, 56 parameters; Li5Ce5Si4N12: a = 1097.78(16), c = 551.43(11) pm, Z = 2, R1 = 0.0334, 748 data, 56 parameters]. The nitridosilicate substructure consists of infinite nonbranched zweier single‐chains of vertex sharing SiN4 tetrahedra running parallel to [001]. The chains exhibit a stretching factor fS = 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 7Li solid‐state MAS NMR investigations are reported.