SrInGe and EuInGe:  New Zintl Phases with an Unusual Anionic Network Derived from the ThSi₂ Structure

Abstract

Two new isostructural Zintl phases, EuInGe and SrInGe, are obtained from high-temperature reactions of the pure elements in welded Ta tubes. Both ternary phases crystallize in a new structure type in space group Pnma (No. 62), with a = 4.921(1) A, b = 3.9865(9) A, and c = 16.004(3) A for EuInGe; and a = 5.021(1) A, b = 4.0455(9) A, and c = 16.188(4) A for SrInGe. The crystal structures established by single-crystal X-ray diffraction feature zigzag chains of 3-bonded Ge atoms and puckered layers of 4-bonded In atoms. The two structural units are linked into an anionic network with channels composed of 5-membered and 7-membered rings. The channels are filled by the respective divalent cations. The chemical bonding of the anionic [InGe](2)(-) network, derived from a one-electron oxidative distortion of the alpha-ThSi(2) structure, is explained using extended-Hückel band structure calculations. Magnetic measurements indicate that EuInGe exhibits Curie-Weiss paramagnetic behavior above 35 K and antiferromagnetic behavior below 35 K. The calculated effective moment, mu(eff) = 8.11 mu(B), of EuInGe and the diamagnetic behavior of SrInGe are consistent with the oxidation states of Eu(II) and Sr(II), respectively.

Synthesis and structural characterization of A3In2Ge4 and A5In3Ge6 (A=Ca, Sr, Eu, Yb)—New intermetallic compounds with complex structures, exhibiting Ge–Ge and In–In bonding

“…However, longer InGe distances, thereby weaker In-Ge bonding interactions are observed in the square-planar [InGe 4 ] fragment (Table 4). The Ge-Ge contacts (d Ge-Ge ¼2.528(2)-2.550(3)Å) match very well with those reported for single-bonded germanium, such as in CaGe 2 [16], SrInGe [7], EuGe 2 [14], Ca 5 Ge 3 [31], SrGe 2 [32], Ca 2 LiInGe 2 and Sr 2 LiInGe 2 [11]. All In-Ge and Ge-Ge bond distances in (Sr 1-x Ca x ) 5 In 3 Ge 6 increase slightly as the composition becomes Sr-richer.…”

“…Other rare-earth metal rich compounds, such as the body-centered tetragonal RE 3 (In,Ge) 5 (In 5 Bi 3 type, Pearson symbol tI32) [4], RE 3 (In,Ge) 2 (Gd 3 Ga 2 type, Pearson symbol tI80) [4b,5], and RE 11 (In,Ge) 10 (Ho 11 Ge 10 type, Pearson symbol tI84) [4a,6], appear to form with La and Ce only. The nominally divalent Eu is reported to form EuInGe (own orthorhombic type, Pearson's symbol oP12), isostructural with SrInGe [7]. Two other relatively common structure types, that of the cubic clathrate-I (Pearson symbol cP54) and clathrate-IX (Pearson symbol cP132) are epitomized by Ba 8 (In,Ge) 46 [8] and Ba 6 (In,Ge) 25 [9], respectively.…”

Ba5(Al/Ga)5(Sn/Pb): Neue Verbindungen an der Zintl-Grenze / Ba5(Al/Ga)5(Sn/Pb): New Compounds at the Zintl Border

“…Diese Verbindungen leiten sich strukturell zum größ-ten Teil von den binären Randverbindungen AM (CrB-Typ), AM 2 (A II = Ca, Sr, Ba; M IV = Si, Ge; [1 -3]) sowie Ba 10 Al 3 Ge 7 [4] mit trigonal-planar koordiniertem Al und Ca 3 Al 2 Ge 3 [3]. Wiederum von den binären AM 2 -Verbindungen abgeleitet sind die 1 : 1 : 1-Gallide A II Ga(Si/Ge) [5] (verzerrter AlB 2 -Typ) sowie die Indide SrInGe (verzerrter ThSi 2 -Typ, [6]) und Ca 2 SrIn 2 Ge (Variante des CrB-Typs, [7] …”

Intermetallics as Zintl Phases: Yb2Ga4Ge6 and RE3Ga4Ge6 (RE=Yb, Eu): Structural Response of a [Ga4Ge6]4− Framework to Reduction by Two Electrons

“…They include the above-mentioned Eu 4 Ga 8 Ge 16 , EuGa 2 AE x Ge 4 AE x [27] and EuInGe. [28] Abstract: Two new intermetallic compounds, Yb 2 Ga 4 Ge 6 and Yb 3 Ga 4 Ge 6 , were obtained from reactions in molten Ga. A third compound, Eu 3 Ga 4 Ge 6 , was produced by direct combination of the elements. The crystal structures of these compounds were studied by single-crystal X-ray diffraction.…”