The Zintl Phases Eu₃Mg₅Si₅ and Eu₃Mg₅Ge₅

Abstract

The Zintl phases Eu 3 Mg 5 Si 5 and Eu 3 Mg 5 Ge 5 were synthesized by high-frequency melting of the elements in sealed tantalum tubes. Both of their structures have been refined from X-ray single crystal diffractometer data:

Carbon, silicon, germanium, tin and lead

“…The structural complexity and the simple surprise continue to make Zintl clusters and their near relatives a source of fascination and interest. New Zintls of the Sr 12 Mg 17.8 Li 2.2 Si 20 type, Eu 3 Mg 5 E 5 (E = Si or Ge) have been reported from the reaction of the elements 69 and the neutral Zintl Ge 9 {Si(SiMe 3 )} 3 SnPh 3 from the reaction of Ph 3 SnCl and the previously reported K[Ge 9 {Si(SiMe 3 )} 3 ]. The substitution of Zintl anions by reaction of the parent Ge 9 4À or derivatives with cationic species has never before been used to prepare such a tetrasubstituted neutral species.…”

Structure and Bonding of an Intergrowth Phase Ca7Ag2+xGe7–x (x ≈ 2/3) Featuring a Zintl‐Type Polyanionic Chain

“…Nevertheless, the compound is one electron deficient according to the Zintl–Klemm concept although, surprisingly, LMTO band structure calculations indicated that the bonding is fully optimized within the anionic substructure. The trimeric unit Ge 3 8– is observed in the electron precise Eu 3 Mg 5 Ge 5 24 as well as in the electron deficient Sr 12 Mg 17.9 Li 2.1 Ge 20 ,25 coexisting with isolated Ge 4– in both cases. The linear Ge 5 12– pentamer has been elusive so far, but is expected in the n = 5 member of the homologous series to represent the missing link between the Ge 4 10– four‐ and Ge 6 14– six‐membered chains.…”

Uncovering new transition metal Zintl phases by cation substitution: the crystal chemistry of Ca3CuGe3 and Ca2+nMnxAg2−x+zGe2+n−z (n = 3, 4)

“…The quantitative synthesis of corresponding Ca/(Li,Mg)/Ge phases was also challenging. [10][11][12] As their structures are so closely related, it is difficult to distinguish the homologous structures between each other or with their parent-structures from X-ray powder diffraction patterns. Therefore, the characterization of our structures is limited essentially to single crystal diffraction and qualitative chemical composition by EDS.…”

“…These AE/M/Tt systems were intensively investigated by Nesper and co-workers. [10][11][12] Previously, the complete replacement of small polarizing Li by Ag in the Ca-M-Ge germanide systems resulted in a new series of structures, Ca 2+n M 2+z Ge 2+n−z (M = Ag, Mg), which are built up by linear intergrowth of slabs cut from the parent structures, CaM 1+z Ge 1−z (AlB 2 or TiNiSi type) and CaGe (CrB type). [13][14][15][16] Our next attempt was toward similar isovalent replacement of Mg by divalent TM elements like Mn and Cd.…”

“…Their crystal chemistry can be understood within the Zintl-Klemm concept, and empirical 'structure directing rules' established by Nesper. [10][11][12] In addition, the bonding characteristics of Ca 3 CuGe 3 and, for comparison, the analogue Ca 3 Ag 1+z Ge 3-z (x ~ 1/3) reported previously, are investigated with the help of electronic band structure calculations obtained by density functional theory (DFT) using the LMTO code on idealized fully ordered models "Ca 3 MGe 3 " (Sc 3 NiSi 3 type with M = Cu, Ag). 13…”