ChemInform Abstract: Synthesis, Crystal Chemistry, and Magnetic Properties of RE₇Li₈Ge₁₀ and Ln₁₁Li₁₂Ge₁₆ (Ln: La—Nd, Sm): New Members of the [LnGe₂]_n[LnLi₂Ge]_m Homologous Series.

Abstract

Synthesis, Crystal Chemistry, and Magnetic Properties of RE 7 Li 8 Ge 10 and Ln11Li12Ge16 (Ln: La-Nd, Sm): New Members of the [LnGe2]n[LnLi2Ge]m Homologous Series. -The title compounds are prepared from stoichiometric mixtures of the elements (Nb tubes, 1223-1273 K, 5 h) and characterized by powder and single crystal XRD, magnetic measurements, and TB-LMTO-ASA calculations. Their structures can be rationalized as linear intergrowths of imaginary LnLi 2 Ge (MgAl 2 Cu structure type) and LnGe2 (AlB2 structure type) slabs. Ln7Li8Ge10 (Ln: La-Nd, Sm) compounds crystallize in the orthorhombic space group Cmmm with Z = 2, and the compounds Ln11Li12Ge16 (Ln: Ce-Nd) crystallize in the orthorhombic space group Immm with Z = 2. Ln7Li8Ge10 (Ln: Ce, Pr) exhibit Curie-Weiss paramagnetism in the high-temperature regime. -(GUO, S.-P.; YOU, T.-S.; JUNG, Y.-H.; BOBEV*, S.; Inorg. Chem. 51 (2012) 12, 6821-6829, http://dx.doi.org/10.1021/ic300566x ; Dep. Chem. Biochem., Univ. Del., Newark, DE 19716, USA; Eng.) -W. Pewestorf 38-003

Intricate Li–Sn Disorder in Rare-Earth Metal–Lithium Stannides. Crystal Chemistry of RE3Li4–xSn4+x (RE = La–Nd, Sm; x < 0.3) and Eu7Li8–xSn10+x (x ≈ 2.0)

“…In all cases, small amounts of side products were present (a representative PXRD pattern is provided in the Supporting Information). Also, unlike the germanides, where thus far four families of compounds belonging to the homologous series [REGe 2 ] n [RELi 2 Ge] m (RE = La–Nd, Sm) have been characterized, namely, RE 2 Li 2 Ge 3 , RE 3 Li 4 Ge 4 , RE 7 Li 8 Ge 10 , and RE 11 Li 12 Ge 16 , the stannide chemistry appears to be limited only to one family. All attempts to make other members were unsuccessful.…”

“…The stannide Eu 7 Li 8– x Sn 10+ x also exists, but with the “7–8–10” structure (N.B. Eu 7 Li 8– x Ge 10+ x is not known to date), and the rare-earth metal in it is divalent (electronic configuration [Xe]­4f 7 ). Notably, Eu 7 Li 8– x Sn 10+ x is only the second example, after LiMgEu 2 Sn 3 (Ce 2 Li 2 Ge 3 type), of a Eu-bearing compound adopting similar structure.…”

“…Their structures are based on imaginary RELi 2 Ge (MgAl 2 Cu-structure type) and REGe 2 (AlB 2 -structure type) slabs . Thus, RE 2 Li 2 Ge 3 with n = 1 and m = 1 and RE 3 Li 4 Ge 4 with n = 1 and m = 2 are the simplest members of the series; RE 7 Li 8 Ge 10 = [REGe 2 ] 3 [RELi 2 Ge] 4 and RE 11 Li 12 Ge 16 = [REGe 2 ] 5 [RELi 2 Ge] 6 are higher homologues . The latter structures can also be rationalized as intergrowths of the former, as schematically shown in Figure .…”

“…The synthesis and structural characterization of new lithium-containing solid-state compoundssilicides, germanides, stannides, and antimonidesis an ongoing project in our laboratory. − Our focus has been on ternary phases with lithium and alkaline-earth or rare-earth metals, which can be broadly classified as (nearly) valence-precise compounds, i.e., Zintl phases. , For example, not long ago, we identified four families of germanides, RE 2 Li 2 Ge 3 , RE 3 Li 4 Ge 4 , RE 7 Li 8 Ge 10 , and RE 11 Li 12 Ge 16 (RE = La–Nd, Sm), , which are members of an extended homologous series, [REGe 2 ] n [RELi 2 Ge] m . Their structures are based on imaginary RELi 2 Ge (MgAl 2 Cu-structure type) and REGe 2 (AlB 2 -structure type) slabs .…”

“…This compound is isotypic with the germanides RE 7 Li 8 Ge 10 (RE = La–Nd, Sm), which are apparently line compounds and show no signs of Li–Ge disorder . Aliovalent substitution of a nominally trivalent rare-earth metal with the divalent Eu leads to a severe electron imbalance in the structure [ca.…”