Schwarz‐glänzende, spröde Einkristalle von M3AuGe4 mit M = K, Rb, Cs wurden durch Umsetzung von Alkalimetallaziden MN3 mit Goldschwamm und Germaniumpulver bei T = 1120 K synthetisiert. Die Strukturen ...der Verbindungen (Raumgruppe Pmmn, Z = 2, K3AuGe4: a = 6, 655(1)Å, b = 11, 911(2)Å, c = 6, 081(1)Å; Rb3AuGe4: a = 6, 894(1)Å, b = 12, 421(1)Å, c = 6, 107(1)Å; Cs3AuGe4: a = 7, 179(1)Å, b = 12, 993(2)Å, c = 6, 112(2)Å) wurden aus Röntgen‐Einkristall‐Diffraktometerdaten bestimmt. Die elektrisch halbleitenden Verbindungen enthalten ∞1AuGe4‐Ketten, in denen P4‐analoge Ge4‐Tetraeder über μ2‐verbrückende Goldatome mit verzerrt tetraedrischer Koordination am Germaniumatom verknüpft werden.
Zintl‐Compounds with Gold and Germanium: M3AuGe4 with M = K, Rb, Cs
Black, brittle single crystals of M3AuGe4 with M = K, Rb, Cs were synthesized by reactions of alkali metal azides (MN3) with gold sponge and germanium powder at T = 1120 K. The structures of the compounds (space group Pmmn, Z = 2, K3AuGe4: a = 6.655(1)Å, b = 11.911(2)Å, c = 6.081(1)Å; Rb3AuGe4: a = 6.894(1)Å, b = 12.421(1)Å, c = 6.107(1)Å; Cs3AuGe4: a = 7.179(1)Å, b = 12.993(2)Å, c = 6.112(2)Å) were determined from X‐ray single‐crystal diffractometry data. The semiconducting compounds contain ∞1AuGe4‐chains with P4‐analogous Ge4‐tetrahedra which are connected by μ2‐bridging gold atoms in a distorted tetrahedral Ge‐coordination.
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The first metalated germanide ion and only the second example of a cluster of the rare nido‐10 (iv+iv) structural type, the anion 1, was isolated from the reaction of Ni(CO)2(PPh3)2, K4Ge9, and ...“2.2.2”cryptand in ethylenediamine (en). However, the structure of the Ge10Ni cluster (see picture) is distinctly distorted relative to the ideal nido‐10 (iv+iv) geometry.
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Silberfarbene, spröde Einkristalle der Verbindungen M3AuSn4 mit M = K, Rb, Cs und M3AuPb4 mit M = Rb, Cs wurden durch Umsetzungen von Alkalimetallaziden MN3 mit Goldschwamm und Zinn(Blei)‐pulver bei ...T = 923 K synthetisiert. Die Strukturen der isotypen Verbindungen (Raumgruppe Pmmn, Z = 2) wurden aus Röntgen‐Einkristall‐Diffraktometerdaten bestimmt: K3AuSn4: a = 6,938(1) Å, b = 12,544(1) Å, c = 6,523(1) Å; Rb3AuSn4: a = 7,147(3) Å, b = 13,081(4) Å, c = 6,558(1) Å; Cs3AuSn4: a = 7,459(1) Å, b = 13,707(3) Å, c = 6,597(1) Å; Rb3AuPb4: a = 7,078(1) Å, b = 13,220(2) Å, c = 6,787(1) Å; Cs3AuPb4: a = 7,333(1) Å, b = 13,821(2) Å, c = 6,828(1) Å.
Die Zintl‐Verbindungen M3AuE(14)4 mit E(14) = Sn, Pb enthalten ∞1AuE(14)4‐Ketten, in denen P4‐analoge E(14)4‐Tetraeder über μ2‐verbrückende Goldatome mit verzerrt tetraedrischer E(14)‐Koordination verknüpft werden.
Zintl‐Compounds with Gold: M3AuSn4 with M = K, Rb, Cs and M3AuPb4 with M = Rb, Cs
Silver coloured, brittle single crystals of the compounds M3AuSn4 with M = K, Rb, Cs and M3AuPb4 with M = Rb, Cs were synthesized by reactions of alkali metal azides (MN3) with gold sponge and tin (lead) powder at T = 923 K. The structures of the isotypic compounds (space group Pmmn, Z = 2) were determined from X‐ray single‐crystal diffractometry data (see ‘‘Inhaltsübersicht”︁”︁). The Zintl‐compounds M3AuE(14)4 with E(14) = Sn, Pb contain ∞1AuE(14)4‐chains with P4‐analogous E(14)4‐tetrahedra which are connected by μ2‐bridging gold atoms.
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The title compounds were prepared by solid state reaction of the elemental components. Their crystal structures were determined from single-crystal X-ray diffractometer data. Ag
SiP
: 14̄2d, a = ...652.75(5) pm, c = 855.0(1) pm, Z = 4, R = 0.024 for 611 structure factors and 14 variable parameters; AuSiP: R3m, a = 345.9(1) pm, c = 1720.0(3) pm, Z = 3, R = 0.023 (352 F values, 11 variables). The silicon atoms in Ag
SiP
are tetrahedrally coordinated by phosphorus atoms. The compound might therefore be considered as a phosphidosilicate and its formula can be rationalized as (Ag
Si
(P
. However, Ag
SiP
is not a tetrahedral compound since the phosphorus atoms have five near neighbors (3Ag + 2Si) and the silver atoms are coordinated by three phosphorus atoms in almost trigonal planar coordination. Weak silver-silver bonding is assumed for the shortest Ag-Ag contacts of 318 pm. In AuSiP the gold atoms are in a linear coordination of one silicon (235.5 pm) and one phosphorus atom (232.6 pm). The silicon and phosphorus atoms are tetrahedrally coordinated (3Si + 1 Au and 3P + 1 Au, respectively). Thus, the elements can be assigned oxidation numbers according to the formula Au
Si
. This structure was also refined in the centrosymmetric space group R3̄m, but in this improper setting the silicon and phosphorus atoms occupy one crystallographic site with random occupancy.
Y2AlGe3 wurde durch Erhitzen der Elemente auf 950°C dargestellt und röntgenographisch mit Einkristallmethoden untersucht. Die Verbindung kristallisiert in einer neuen Struktur (Pnma; a = 6,785(1) Å, ...b = 4,189(1) Å, c = 17,676(2) Å; Z = 4) mit einem dreidimensionalen Gerüst aus Al‐ und Ge‐Atomen, in dessen Lücken sich die Y‐Atome befinden. Al ist tetraedrisch von Ge‐Atomen umgeben, die ihrerseits ebene (Ge2−)∞‐Ketten bilden bzw. voneinander isoliert vorliegen. Trotz nicht valenzmäßiger Zusammensetzung gemäß Y3+ Y3+ Al3+ (Ge2)4− Ge4− und metallischer Leitfähigkeit weist Y2AlGe3 die Strukturmerkmale einer Zintl‐Verbindung auf. Diese Interpretation wird gestützt durch Berechnungen der Elektronendichte und Elektronenlokalisierungsfunktion (ELF), die kovalente GeGe‐ und AlGe‐Bindungen zeigen. Die Verbindung wird demnach als metallische Zintl‐Verbindung angesehen. Y2AlGe3 wird bei 4,5 K supraleitend. Isotyp kristallisieren die Verbindungen Ln2AlGe3 (Ln = DyTm) mit den Gitterkonstanten:
Dy2AlGe3: a = 6,785(3) Å, b = 4,171(1) Å, c = 17,665(7) Å
Ho2AlGe3: a = 6,753(2) Å, b = 4,158(1) Å, c = 17,580(4) Å
Er2AlGe3: a = 6,732(1) Å, b = 4,147(3) Å, c = 17,517(3) Å
Tm2AlGe3: a = 6,706(3) Å, b = 4,061(5) Å, c = 17,550(9) Å.
Y2AlGe3 – a Superconductive Metallic Zintl Compound
Y2AlGe3 was prepared by heating the elements (950°C) and investigated by means of single‐crystal X‐ray methods. The compound crystallizes in a new structure (Pnma; a = 6.785(1) Å, b = 4.189(1) Å, c = 17.676(2) Å; Z = 4) with a three‐dimensional framework of Al and Ge atoms and with Y in the cavities. The Al atoms are surrounded tetrahedrally by Ge atoms, which are arranged in the form of planar (Ge2−)∞ chains and isolated from each other respectively. Although Y2AlGe3 is a metallic conductor and no valence compound, it achieves the structural requirements of Zintl's concept. This picture is supported by electrondensity and ELF calculations, which reveals covalent AlGe and GeGe bondings, therefore Y2AlGe3 is interpreted as a metallic Zintl‐Compound, down‐playing the metallic propertys. Y2AlGe3 becomes superconductively at 4.5 K. Isotypic compounds are found for Ln2AlGe3 with Ln = Dy, Ho, Er, and Tm (For lattice constants see “Inhaltsübersicht”).
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