Synthesis and Crystal Structures of the First Quaternary Tantalum Thiogermanates,ATaGeS5 (A = K,Rb, Cs) |
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Authors: | Yongkwan Dong Junghwan Do Hoseop Yun Prof. Dr. |
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Affiliation: | 1. Department of Chemistry, Konkuk University, Seoul 143‐701, Republic of South Korea;2. Division of Energy Systems Research and Department of Chemistry, Ajou University, Suwon 443‐749, Republic of South Korea |
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Abstract: | The new quaternary thiogermanates, ATaGeS5 (A = K, Rb, Cs) were prepared with the use of halide fluxes and the crystal structures of the compounds were determined by single‐crystal X‐ray diffraction methods. The compounds are isostructural and crystallize in space group Pbar{1} of the triclinic system with two formula units in a cell of dimensions: a = 6.937(1) Å, b = 6.950(2) Å, c = 8.844(3) Å, α = 71.07(2)°, β = 78.56(2)°, γ = 75.75(2)°, V = 387.6(2) Å3 for KTaGeS5; a = 6.996(3) Å, b = 7.033(3) Å, c = 8.985(4) Å, α = 70.33(3)°, β = 78.12(4)°, γ = 75.63(4)°, V = 399.6(3) Å3 for RbTaGeS5; a = 7.012(4) Å, b = 7.202(3) Å, c = 9.267(5) Å, α = 68.55(3)°, β = 77.27(4)°, γ = 74.75(4)°, V = 416.2(4) Å3 for CsTaGeS5. The structures of ATaGeS5 (A = K, Rb, Cs) are comprised of anionic infinite two‐dimensional {}_infty^2 [TaGeS5–] layers separated from one another by alkali metal cations (A+). Each layer is made up of tantalum centered sulfur octahedra and pairs of edge‐sharing germanium centered sulfur tetrahedra. The classical charge valence of these compounds should be represented by [A+][(Ta5+)(Ge4+)(S2–)5]. UV/Vis diffuse reflectance measurements indicate that they are semiconductors with optical bandgaps of ca. 2.0 eV. |
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Keywords: | Chalcogens Thiogermanate Halide flux synthesis Structure elucidation X‐ray diffraction |
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