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1. Ca ₂ Ga ₄ Ge ₆ and Ca ₃ Ga ₄ Ge ₆ : Synthesis, Structure, and Electronic Properties

   https://doi.org/10.1002/zaac.202100342  

   Hodge, Kelsey L; Davis, H Olivia; Koster, Karl G; Windl, Wolfgang; Moore, Curtis E; Goldberger, Joshua E (August 2022, Zeitschrift für anorganische und allgemeine Chemie)

   Abstract During the search for transition metal‐free alkyne hydrogenation catalysts, two new ternary Ca−Ga−Ge phases, Ca₂Ga₄Ge₆(Cmc2₁, a=4.1600(10) Å, b=23.283(5) Å, c=10.789(3) Å) and Ca₃Ga₄Ge₆(C2/m, a=24.063(2) Å, b=4.1987(4) Å, c=10.9794(9) Å, β=91.409(4)°), were discovered. These compounds are isostructural to the previously established Yb₂Ga₄Ge₆and Yb₃Ga₄Ge₆analogues, and according to Zintl‐Klemm counting rules, consist of anionic [Ga₄Ge₆]⁴⁻and [Ga₄Ge₆]⁶⁻frameworks in which every Ga and Ge atom would have a formal octet with no Ga−Ga or Ga−Ge π‐bonding. These compounds are metallic, based on temperature dependent electrical resistivity and thermopower measurements for Ca₃Ga₄Ge₆, along with density functional theory calculations for both phases. Unlike the highly active 13‐layer trigonal CaGaGe phase, these new compounds exhibit minimal activity in the semi/full alkyne hydrogenation of phenylacetylene, which is consistent with previous observations that the lack of a formal octet for framework atoms is essential for catalysis in these Zintl‐Klemm compounds. 

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2. Yet Another Case of Lithium Metal Atoms and Germanium Atoms Sharing Chemistry in the Solid State: Synthesis and Structural Characterization of Ba ₂ LiGe ₃

   https://doi.org/10.1002/chem.202302385  

   Ghosh, Kowsik; Bobev, Svilen (December 2023, Chemistry – A European Journal)

   Abstract Several Ba−Li−Ge ternary phases are known and structurally characterized, including the title compound Ba₂LiGe₃. Its structure is reported to contain [Ge₆]¹⁰⁻anions that exhibit delocalized bonding with a Hückel‐like aromatic character. The Ge atoms are in the same plane with the Li atoms, and if both types of atoms are considered as covalently bonded, [LiGe₃]⁴⁻honeycomb‐like layers will result. The latter are separated by slabs of Ba²⁺cations. However, based on the systematic work detailed herein, it is necessary to re‐evaluate the phase as Ba₂Li_1−xGe_3+x(x<0.05). Although small, the homogeneity range is clearly demonstrated in the gradual change of the unit cell for four independent samples. Subsequent characterization by single‐crystal X‐ray diffraction methods shows that the Ba₂Li_1−xGe_3+xstructure, responds to the varied number of valence electrons and the changes are most pronounced for the refined lengths of the Li−Ge and Ge−Ge bonds. Indirectly, the changes in the Ge−Li/Ge distances within layers affect the stacking too, and these changes can be correlated to the variation of thec‐cell parameter. Chemical bonding analysis based on TB‐LMTO‐ASA level calculations affirms the notion for covalent character of the Ge−Ge bonds; the Ba−Ge and Li−Ge interactions also show some degree of covalency. 

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3. Crystal structure characterization and electronic structure of a rare-earth-containing Zintl phase in the Yb–Al–Sb family: Yb ₃ AlSb ₃

   https://doi.org/10.1107/S2053229621005192  

   Shang, Rongqing; Nguyen, An T.; He, Allan; Kauzlarich, Susan M. (June 2021, Acta Crystallographica Section C Structural Chemistry)

   null (Ed.)

   A rare-earth-containing compound, ytterbium aluminium antimonide, Yb 3 AlSb 3 (Ca 3 AlAs 3 -type structure), has been successfully synthesized within the Yb–Al–Sb system through flux methods. According to the Zintl formalism, this structure is nominally made up of (Yb 2+ ) 3 [(Al 1− )( 1b – Sb 2− ) 2 ( 2b – Sb 1− )], where 1b and 2b indicate 1-bonded and 2-bonded, respectively, and Al is treated as part of the covalent anionic network. The crystal structure features infinite corner-sharing AlSb 4 tetrahedra, [AlSb 2 Sb 2/2 ] 6− , with Yb 2+ cations residing between the tetrahedra to provide charge balance. Herein, the synthetic conditions, the crystal structure determined from single-crystal X-ray diffraction data, and electronic structure calculations are reported. 

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4. [Palladium-decabismuth(4+)]-tetrakis(tetrachloridoaluminate) Cluster Compound, [Pd@Bi10][AlCl4]4: Synthesis, Crystal Structure, and Electronic Structure

   https://doi.org/10.3390/M2020  

   Samarakoon, S_M_Gayomi K; Baranets, Sviatoslav (June 2025, Molbank)

   Black, needle-like single crystals of [Pd@Bi10][AlCl4]4 were synthesized in a one-pot reaction between PdCl2, Bi, and BiCl3 at 180 °C in the Lewis acidic ionic liquid (LAIL) medium [BMIm]Cl∙4.2AlCl4 (BMIm = 1-n-butyl-3-methylimidazolium). Single-crystal X-ray diffraction revealed that the compound crystallizes in the triclinic space group P1¯ with the unit cell parameters a = 11.0233(5) Å, b = 26.1892(14) Å, c = 26.2687(14) Å, α = 90.842(2)°, β = 92.1940(10)°, γ = 91.164(2)°, closely matching its platinum-containing analog. The structure features pentagonal antiprismatic [Pd@Bi10]4+ cluster cations charge-balanced by tetrahedral [AlCl4]− anions. Bonding and charge analysis reveal unoptimized Pd–Bi and strong Bi–Bi covalent interactions consistent with electronegativity trends and the previously reported host–guest model. Electronic structure calculations performed with the TB-LMTO-ASA program show that [Pd@Bi10][AlCl4]4 exhibits semiconducting behavior, suggesting a bandgap opening of 0.71 eV. 

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5. Synthesis, crystal and electronic structure of BaLixCd13–x (x ≈ 2)

   https://doi.org/10.3389/fchem.2022.991625  

   Peng, Wanyue; Baranets, Sviatoslav; Bobev, Svilen (September 2022, Frontiers in Chemistry)

   A new ternary phase has been synthesized and structurally characterized. BaLi x Cd 13– x ( x ≈ 2) adopts the cubic NaZn 13 structure type (space group Fm 3 ¯ c , Pearson symbol cF 112) with unit cell parameter a = 13.5548 (10) Å. Structure refinements from single-crystal X-ray diffraction data demonstrate that the Li atoms are exclusively found at the centers of the Cd 12 -icosahedra. Since a cubic BaCd 13 phase does not exist, and the tetragonal BaCd 11 is the most Cd-rich phase in the Ba–Cd system, BaLi x Cd 13– x ( x ≈ 2) has to be considered as a true ternary compound. As opposed to the typical electron count of ca. 27 e -per formula unit for many known compounds with the NaZn 13 structure type, BaLi x Cd 13– x ( x ≈ 2) only has ca. 26 e -, suggesting that both electronic and geometric factors are at play. Finally, the bonding characteristics of the cubic BaLi x Cd 13– x ( x ≈ 2) and tetragonal BaCd 11 are investigated using the TB-LMTO-ASA method, showing metallic-like behavior. 

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