Crystal Structure, 7 Li NMR, and Structural Relationship of Two Rare‐Earth Metal Richer Polar Intermetallics: La 15 Ge 9 Li 1.50(16) and La 7 Ge 3

Two novel polar intermetallic compounds have been synthesized by a high‐temperature reaction method, and their crystal structures have been characterized by both single‐crystal and powder X‐ray diffractions. La 15 Ge 9 Li 1 .50(16) crystallizes in the hexagonal space group P 6 3 mc ( Z = 2, Pearson code hP 52) with nine crystallographically independent sites in the unit cell, and the lattice parameters are a = 15.516(2) and c = 6.895(2) Å. The overall crystal structure can be described as a √3 × √3 × 1 superstructure of the parent compound La 5 Ge 3 adopting the Mn 5 Si 3 ‐type, and such a superstructure transformation should be attributed to the particular ordering patterns of interstitial Li atoms at the Wyckoff 2 a and 2 b sites with different occupation factors. La 7 Ge 3 also crystallizes in the hexagonal P 6 3 mc space group ( Z = 2, Pearson code hP 20) with three La and one Ge non‐equivalent sites in the unit cell. The lattice parameters are a = 10.666(1) and c = 6.357(1) Å. The crystal structure of La 7 Ge 3 shares some similarities with La 15 Ge 9 Li 1.50(16) and its parent compound La 5 Ge 3 , such as the one‐dimensional (1D) zigzag confacial La 6 octahedra chains and the 1D zigzag La atomic chains. Theoretical investigations using tight‐binding linear muffin‐tin orbital (LMTO) method provide a comprehensive understanding about electronic structures and chemical bonding of two title compounds based upon density of states (DOS) and crystal orbital Hamilton population (COHP) analyses. The solid‐state 7 Li NMR spectrum measurement proves the existence of two independent interstitial Li positions at two distinctive octahedral sites in La 15 Ge 9 Li 1.50(16) .