σ-Aromaticity-Induced Stabilization of Heterometallic Supertetrahedral Clusters [Zn6Ge16]4− and [Cd6Ge16]4−

In this work, the largest heterometallic supertetrahedral clusters, [Zn₆Ge₁₆]⁴⁻ and [Cd₆Ge₁₆]⁴⁻, were directly self-assembled through highly-charged [Ge₄]⁴⁻ units and transition metal cations, in which 3-center–2-electron σ bonding in Ge₂Zn or Ge₂Cd triangles plays a vital role in the stabilization of the whole structure. The cluster structures have an open framework with a large central cavity of diameter 4.6 Å for Zn and 5.0 Å for Cd, respectively. Time-dependent HRESI-MS spectra show that the larger clusters grow from smaller components with a single [Ge₄]⁴⁻ and ZnMes₂ units. Calculations performed at the DFT level indicate a very large HOMO–LUMO energy gap in [M₆Ge₁₆]⁴⁻ (2.22 eV), suggesting high kinetic stability that may offer opportunities in materials science. These observations offer a new strategy for the assembly of heterometallic clusters with high symmetry.     

On the Nature of Bridging Metal Atoms in Intermetalloid Clusters: Synthesis and Structure of the Metal‐Atom‐Bridged Zintl Clusters [Sn(Ge9)2]4− and [Zn(Ge9)2)]6−

The addition of Sn and Zn ions to [Ge₉] clusters by reaction of [Ge₉]^4? with SnPh₂Cl₂, ZnCp*₂ (Cp*=pentamethylcyclopentadienyl), or Zn₂[HC(Ph₂P=NPh)₂]₂ is reported. The resulting Sn‐ and Zn‐bridged clusters [(Ge₉)M(Ge₉)]^q? (M=Sn, q=4; M=Zn, q=6) display various coordination modes. The M atoms that coordinate to the open square of a C_4v‐symmetric [Ge₉] cluster form strong covalent multicenter M?Ge bonds, in contrast to the M atoms coordinating to triangular cluster faces. Molecular orbital analyses show that the M atoms of the Ge₉M fragments coordinate to a second [Ge₉] cluster with similar orbitals but in different ways. The [Ge₉Sn]^2?unit donates two electrons to the triangular face of a second [Ge₉]^2? cluster with D_3h symmetry, whereas [Ge₉Zn]^2?acts as an electron acceptor when interacting with the triangular face of a D_3h‐symmetric [Ge₉]^4? unit.     

Atom Exchange Versus Reconstruction: (GexAs4−x)x− (x=2, 3) as Building Blocks for the Supertetrahedral Zintl Cluster [Au6(Ge3As)(Ge2As2)3]3−

The Zintl anion (Ge₂As₂)^2? represents an isostructural and isoelectronic binary counterpart of yellow arsenic, yet without being studied with the same intensity so far. Upon introducing [(PPh₃)AuMe] into the 1,2‐diaminoethane (en) solution of (Ge₂As₂)^2?, the heterometallic cluster anion [Au₆(Ge₃As)(Ge₂As₂)₃]^3? is obtained as its salt [K(crypt‐222)]₃[Au₆(Ge₃As)(Ge₂As₂)₃]?en?2 tol ( 1 ). The anion represents a rare example of a superpolyhedral Zintl cluster, and it comprises the largest number of Au atoms relative to main group (semi)metal atoms in such clusters. The overall supertetrahedral structure is based on a (non‐bonding) octahedron of six Au atoms that is face‐capped by four (Ge_xAs_4?x)^x? (x=2, 3) units. The Au atoms bind to four main group atoms in a rectangular manner, and this way hold the four units together to form this unprecedented architecture. The presence of one (Ge₃As)^3? unit besides three (Ge₂As₂)^2? units as a consequence of an exchange reaction in solution was verified by detailed quantum chemical (DFT) calculations, which ruled out all other compositions besides [Au₆(Ge₃As)(Ge₂As₂)₃]^3?. Reactions of the heavier homologues (Tt₂Pn₂)^2? (Tt=Sn, Pb; Pn=Sb, Bi) did not yield clusters corresponding to that in 1 , but dimers of ternary nine‐vertex clusters, {[AuTt₅Pn₃]₂}^4? (in 2 – 4 ; Tt/Pn=Sn/Sb, Sn/Bi, Pb/Sb), since the underlying pseudo‐tetrahedral units comprising heavier atoms do not tend to undergo the said exchange reactions as readily as (Ge₂As₂)^2?, according to the DFT calculations.     

Na12Ge17: A Compound with the Zintl Anions [Ge4]4— and [Ge9]4— — Synthesis,Crystal Structure,and Raman Spectrum

Na₁₂Ge₁₇ is prepared from the elements at 1025 K in sealed niobium ampoules. The crystal structure reinvestigation reveals a doubling of the unit cell (space group:P2₁/c; a = 22.117(3)Å, b = 12.803(3)Å, c = 41.557(6)Å, β = 91.31(2)°, Z = 16; Pearson code: mP464), furthermore, weak superstructure reflections indicate an even larger C‐centred monoclinic cell. The characteristic structural units are the isolated cluster anions [Ge₉]^4— and [Ge₄]^4— in ratio 1:2, respectively. The crystal structure represents a hierarchical cluster replacement structure of the hexagonal Laves phase MgZn₂ in which the Mg and Zn atoms are replaced by the Ge₉ and Ge₄ units, respectively. The Raman spectrum of Na₁₂Ge₁₇ exhibits the characteristic breathing modes of the constituent cluster anions at ν = 274 cm^—1 ([Ge₉]^4—) and ν = 222 cm^—1 ([Ge₄]^4—) which may be used for identification of these clusters in solid phases and in solutions. Raman spectra further prove that Na₁₂Ge₁₇ is partial soluble both in ethylenediamine and liquid ammonia. The solution and the solid extract contain solely [Ge₉]^4—. The remaining insoluble residue is Na₄Ge₄. By heating the solvate Na₄Ge₉(NH₃)_n releases NH₃ and decomposes irreversibly at 742 K, yielding Na₁₂Ge₁₇ and Ge.     

Binary alkali metal compounds with the zintl anions [Ge9]4− and [Sn9]4−

The binary germanides M₁₂Ge₁₇ and M₄Ge₉ (M ? Na, K, Rb, Cs) and the stannides M₁₂Sn₁₇ and M₄Sn₉ (M ? K, Rb, Cs) were identified by a combination of direct synthesis, thermogravimetric analysis, vibrational spectroscopy, X-ray powder data and single crystal structure analysis. The M₁₂E₁₇ phases contain the cluster anions [E₉]^4? and [E₄]^4? in the ratio 1:2, forming a hierarchical structure with the cluster anions at the atomic positions of the hexagonal Laves phase MgZn₂. Like the M₄E₄ phases, the M₄Ge₉ compounds are hierarchical derivatives of the cubic Cr₃Si structure but with [Ge₉]^4? anions. The thermogravimetric analyses give strong evidence for the existence of at least one more phase with [E₉]^4? and [E₄]^4? clusters and of the clathrate phases M₆E₁₃₆ in addition to the well-known M₈E₄₄□₂ chlathrates.     

Retention of the Zn−Zn bond in [Ge9Zn−ZnGe9]6− and Formation of [(Ge9Zn)−(Ge9)−(ZnGe9)]8− and Polymeric [−(Ge9Zn)2−−]

Reactions of Zn^I₂L₂ (where L=[HC(PPh₂NPh)]⁻) with solutions of the Zintl phase K₄Ge₉ in liquid ammonia lead to retention of the Zn−Zn bond and formation of the anion [(η⁴‐Ge₉)Zn−Zn(η⁴‐Ge₉)]⁶⁻, representing the first complex with a Zn−Zn unit carrying two cluster entities. The trimeric anion [(η⁴‐Ge₉)Zn{μ₂(η¹:η¹Ge₉)}Zn(η⁴‐Ge₉)]⁸⁻ forms as a side product, indicating that oxidation reactions also take place. The reaction of Zn₂Cp*₂ (Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) with K₄Ge₉ in ethylenediamine yielded the linear polymeric unit {[Zn[μ₂(η⁴:η¹Ge₉)]}²⁻ with the first head‐to‐tail arrangement of ten‐atom closo ‐clusters. All anions were obtained and structurally characterized as [A (2.2.2‐crypt)]⁺ salts (A =K, Rb). Copious computational analyses at a DFT‐PBE0/def2‐TZVPP/PCM level of theory confirm the experimental structures and support the stability of the two hypothetical ten vertex cluster fragments closo ‐[Ge₉Zn]²⁻ and (paramagnetic) [Ge₉Zn]³⁻.     

Tetrarubidium Nonagermanide(4–) Ethylenediamine,Rb4[Ge9][en]

Tetrarubidiumnonagermanid(4–)-ethylendiamin, Rb₄[Ge₉][en] Orange-farbene Kristalle von Rb₄[Ge₉][en] erhält man nach der Austauschreaktion einer Lösung von ,NaGe_2.25‘ (precursor) in Ethylendiamin (en) mit festem RbI bei 360 K und nachfolgender langsamer Abkühlung. Die Verbindung ist äußerst empfindlich gegen Oxidation und Hydrolyse. Der thermische Abbau im dynamischen Vakuum beginnt mit der vollständigen Abgabe von en bei 350 K. Es folgt die Sublimation von Rubidium in vier weiteren Stufen (Rb₈Ge₂₅, Rb₈Ge₄₄, Rb_xGe₁₃₆ mit x È 16, Ge). Das Ramanspektrum zeigt die charakteristischen Banden des Anions [Ge₉]^4– bei 151, 163, 185 und 222 cm^–1. Rb₄[Ge₉][en] kristallisiert in einem neuen Strukturtyp (Raumgruppe P2₁/m; a = 15.353 Å, b = 16.434 Å, c = 15.539 Å, β = 113.75°; Z = 6; Pearsonsymbol mP198-40), der als hierarchische Variante der Strukturen von Al₄YbMo₂ und CrB₄ (hierarchische Basistypen, „initiators”︁) beschrieben werden kann, indem Atome partiell durch Aggregate ersetzt werden: B₄[□][Cr] ≙ Al₄[Yb][Mo]₂ ≙ Rb₄[Ge₉][en]_1–2. Drei kristallographisch unabhängige [Ge₉]^4–-Cluster sind in ein vierbindiges 46⁵-Netz aus Rb-Atomen eingebettet, ein Netzwerk kondensierter Tetraasterane. Die Cluster sind verzerrte überkappte tetragonale Antiprismen mit D₁(Ge–Ge) = 2.57 Å (16 Ç ) und D₂(Ge–Ge) = 2.84 Å (4 Ç ). Die Atome der Cluster mit D₁ und D₂ liegen auf der Oberfläche eines Rotationsellipsoids (a = b = 2.136 Å, c = 2.431 Å). Die en-Moleküle befinden sich in offenen Kanälen entlang [1¯ 0 1]. Die Koordinationen [Ge₉]Rb_12/4 und Rb [Ge₉]_4/12 en_2/8 zeigen, daß beim ersten Schritt der Solvatisierung Kationen und Clusteranionen nicht voneinander getrennt werden.     

[Ge2]4− Dumbbells with Very Short Ge−Ge Distances in the Zintl Phase Li3NaGe2: A Solid‐State Equivalent to Molecular O2

The novel ternary Zintl phase Li₃NaGe₂ comprises alkali‐metal cations and [Ge₂]^4? dumbbells. The diatomic [Ge₂]^4? unit is characterized by the shortest Ge?Ge distance (2.390(1) Å) ever observed in a Zintl phase and thus represents the first Ge=Ge double bond under such conditions, as also suggested by the (8?N) rule. Raman measurements support these findings. The multiple‐bond character is confirmed by electronic‐structure calculations, and an upfield ⁶Li NMR shift of ?10.0 ppm, which was assigned to the Li cations surrounded by the π systems of three Ge dumbbells, further underlines this interpretation. For the unperturbed, ligand‐free dumbbell in Li₃NaGe₂, the π‐ bonding p_y and p_z orbitals are degenerate as in molecular oxygen, which has singly occupied orbitals. The partially filled π‐type bands of the neat solid Li₃NaGe₂ cross the Fermi level, resulting in metallic properties. Li₃NaGe₂ was synthesized from the elements as well as from binary reactants and subsequently characterized crystallographically.     

Heterometallic Clusters [CuSn3S9]5− and [Cu6Sn6S20]10−: Solvothermal Synthesis and Characterization of 4f–3d Thiostannates

Two types of 4f–3d thiostannates with general formula [Hen]₂[Ln(en)₄(CuSn₃S₉)] ? 0.5 en ( Ln1 ; Ln=La, 1 ; Ce, 2 ) and [Hen]₄[Ln(en)₄]₂[Cu₆Sn₆S₂₀] ? 3 en ( Ln2 ; Ln=Nd, 3 ; Gd, 4 ; Er, 5 ) were prepared by reactions of Ln₂O₃, Cu, Sn, and S in ethylenediamine (en) under solvothermal conditions between 160 and 190 °C. However, reactions performed in the range from 120 to 140 °C resulted in crystallization of [Sn₂S₆]^4? compounds and CuS powder. In 1 and 2 , three SnS₄ tetrahedra and one CuS₃ triangle are joined by sharing sulfur atoms to form a novel [CuSn₃S₉]^5? cluster that coordinates to the Ln³⁺ ion of [Ln(en)₄]³⁺ (Ln=La, Ce) as a monodentate ligand. The [CuSn₃S₉]^5? unit is the first thio‐based heterometallic adamantane‐like cluster coordinating to a lanthanide center. In 3 – 5 , six SnS₄ tetrahedra and six CuS₃ triangles are connected by sharing common sulfur atoms to form the ternary [Cu₆Sn₆S₂₀]^10? cluster, in which a Cu₆ core is enclosed by two Sn₃S₁₀ fragments. The topological structure of the novel Cu₆ core can be regarded as two Cu₄ tetrahedra joined by a common edge. The Ln³⁺ ions in Ln1 and Ln2 are in nine‐ and eightfold coordination, respectively, which leads to the formation of the [CuSn₃S₉]^5? and [Cu₆Sn₆S₂₀]^10? clusters under identical synthetic conditions. The syntheses of Ln1 and Ln2 show the influence of the lanthanide contraction on the quaternary Ln/Cu/Sn/S system in ethylenediamine. Compounds 1 – 5 exhibit bandgaps in the range of 2.09–2.48 eV depending on the two different types of clusters in the compounds. Compounds 1 , 3 , and 4 lost their organic components in the temperature range of 110–350 °C by multistep processes.     

Studies on the Reactivity of [Ge9]4− towards [Fe(cot)(CO)3]: Synthesis and Characterization of [Ge8Fe(CO)3]3− and of the Anionic Organometallic Species [Fe(cot)(CO)3]−

Reaction of cyclooctatetraene (COT) iron(II) tricarbonyl, [Fe(cot)(CO)₃], with one equivalent of K₄Ge₉ in ethylenediamine (en) yielded the cluster anion [Ge₈Fe(CO)₃]^3? which was crystallographically‐characterized as a [K(2,2,2‐crypt)]⁺ salt in [K(2,2,2‐crypt)]₃[Ge₈Fe(CO)₃]. The chemically‐reduced organometallic species [Fe(η³‐C₈H₈)(CO)₃]^? was also isolated as a side‐product from this reaction as [K(2,2,2‐crypt)][Fe(η³‐C₈H₈)(CO)₃]. Both species were further characterized by EPR and IR spectroscopy and electrospray mass spectrometry. The [Ge₈Fe(CO)₃]^3? cluster anion represents an unprecedented functionalized germanium Zintl anion in which the nine‐atom precursor cluster has lost a vertex, which has been replaced by a transition‐metal moiety.     

IrIn7GeO8 = [IrIn6](GeO4)(InO4) und Verbindungen der Mischkristallreihe [IrIn6](Ge1+xIn1−4x/3O8) (0 ≤ x ≤ 0.75) – erste Oxide mit [IrIn6]‐Oktaedern

IrIn₇GeO₈ = [IrIn₆](GeO₄)(InO₄) and Compounds of the Solid Solution Series [IrIn₆](Ge_1+xIn_1?4x/3O₈) (0 ≤ x ≤ 0.75): First Oxides containing [IrIn₆] Octahedra The low valent indiumoxides IrIn₇GeO₈ = [IrIn₆](GeO₄)(InO₄) and [IrIn₆](Ge_1+xIn_1?4x/3O₈) (0 x ≤ 0.75) are formed by heating intimate mixtures of Ir, In, In₂O₃ and GeO₂ in corundum crucibles under an atmosphere of argon (1420 K, 70 h). The compounds are black and semiconducting. X‐ray powder diffraction patterns can be indexed on the basis of a face centered cubic unit cell with lattice parameters ranging from a = 1012.3(1) pm (x = 0) to a = 1007.3(1) pm (x = 0.75). Characteristic building units in [IrIn₆](Ge_1+xIn_1?4x/3O₈) are isolated [IrIn₆]⁹⁺ octahedra with short Ir‐In distances of 253.5 pm, which are linked via [GeO₄]^4? and [InO₄]^5? tetrahedra to a three dimensional framework. Starting from IrIn₇GeO₈ = [IrIn₆](GeO₄)(InO₄), the isoelectronic substitution of 4 In³⁺ ions by 3 Ge⁴⁺ ions and one Ge‐vacancy leads to the formation of a solid solution series [IrIn₆](GeO₄)_1+x(O₄)_x/3(InO₄)_1?4x/3, which shows a slight decrease in the cubic lattice parameter with increasing x. According to Rietveld refinements the structure of [IrIn₆](GeO₄)(InO₄) exhibits a statistical distribution of the tetrahedrally coordinated Ge and In atoms ( , R(prof.) = 4.4 %, R(int.) = 2.5 %). The crystal and electronic structures of [IrIn₆](GeO₄)(InO₄) are discussed on the basis of first principles electronic structure calculations.     

[Ge4O6Te4]4—, an Adamantanoid Oxotellurido Germanate(IV) with a Central Ge4O6 Core

[Mn(en)₃]₂[Ge₄O₆Te₄]·1.5en ( 1 ) and (enH)₃[Mn(en)₃]₃[Ge₄O₆Te₄]₂I·4.7en ( 2 ) may be prepared at 150 °C by solvothermal reaction of elemental Ge and Te with Mn(OOCCH₃)₂ ·4H₂O in the presence of [CH₃)₄N]I as a mineralizer in respectively superheated ethylenediamine (en) or an en/CH₃OH (3:2) mixture. Both contain the novel [Ge₄O₆Te₄]^4— anion with a central adamantanoid Ge₄O₆ core and four terminal Te atoms and represent the first examples of such a mixed [M₄E₆E₄′]^4— anion (M = Si‐Sn; E = O‐Te). As a result of their increased polarity, the Ge‐Te bonds of 2 are markedly shorter (2.438 — 2.462Å) than those previously reported for telluridogermanates(IV).     

Diversity of Strontium Nitridogermanates(IV): Novel Sr4[GeN4], Sr8Ge2[GeN4], and Sr17Ge2[GeN3]2[GeN4]2

Single crystals of three new strontium nitridogermanates(IV) were grown in sealed niobium ampules from sodium flux. Dark red Sr₄[GeN₄] crystallizes in space group P2₁/c with a = 9.7923(2) Å, b = 6.3990(1) Å, c = 11.6924(3) Å and β = 115.966(1)°. Black Sr₈Ge₂[GeN₄] contains Ge^4– anions coexisting with [Ge^IVN₄]^8– tetrahedra and adopts space group Cc with a = 10.1117(4) Å, b = 17.1073(7) Å, c = 10.0473(4) Å and β = 115.966(1)°. Black Sr₁₇Ge₆N₁₄ features the same anions alongside trigonal planar [Ge^IVN₃]^5– units. It crystallizes in P1 with a = 7.5392(1) Å, b = 9.7502(2) Å, c = 11.6761(2) Å, α = 103.308(1)°, β = 94.651(1)° and γ = 110.248(1)°.     

Functionalization of [Ge9] with Small Silanes:[Ge9(SiR3)3]– (R = iBu,iPr, Et) and the Structures of (CuNHCDipp)[Ge9{Si(iBu)3}3], (K‐18c6)Au[Ge9{Si(iBu)3}3]2, and (K‐18c6)2[Ge9{Si(iBu)3}2]

Novel silylation reactions at [Ge₉] Zintl clusters starting from the chlorosilanes SiR₃Cl (R = iBu, iPr, Et) and the Zintl phase K₄Ge₉ are reported. The formation of the tris‐silylated anions [Ge₉(SiR₃)₃]^– [R = iBu ( 1a ), iPr ( 1b ), Et ( 1c )] by heterogeneous reactions in acetonitrile was monitored by ESI‐MS measurements. For R = iBu ¹H, ¹³C and ²⁹Si NMR experiments confirmed the exclusive formation of 1a . Subsequent reactions of 1a with CuNHC^DippCl and Au(PPh₃)Cl result in formation of the neutral metal complex (CuNHC^Dipp)[Ge₉{Si(iBu)₃}₃]·0.5 tol ( 2 ·0.5 tol) and the metal bridged dimeric unit {Au[Ge₉{Si(iBu)₃}₃]₂}^– ( 3a ), isolated as a (K‐18c6)⁺ salt in (K‐18c6)Au[Ge₉{Si(iBu)₃}₃]₂·tol ( 3 ·tol), respectively. Finally, from a toluene/hexane solution of 1a in presence of 18‐crown‐6, crystals of the compound (K‐18c6)₂[Ge₉{Si(iBu)₃}₂]·tol ( 4 ·tol), containing the bis‐silylated cluster anion [Ge₉(Si(iBu)₃)₂]^2– ( 4a ), were obtained. The compounds 2 ·0.5 tol, 3 ·tol and 4 ·tol were characterized by single‐crystal structure determination.     

catena‐Poly­[[di­aqua­cadmium(II)]‐μ‐5‐carboxyimidazole‐4‐carboxylato‐κ4N1,O5:O4,N3]

A new cadmium coordination polymer, [Cd(C₅H₂N₂O₄)(H₂O)₂]_n, possesses a one‐dimensional zigzag chain structure built from Cd^II centers bridged sequentially by pairs of O and N atoms of the 5‐carboxyimidazole‐4‐carboxylate ligand. The Cd^II center is in a distorted octahedral geometry, being coordinated by two O atoms from two coordinated water mol­ecules [Cd—O = 2.322 (7) and 2.364 (7) Å], and by two N atoms [Cd—N = 2.222 (6) and 2.232 (6) Å] and two carboxyl O atoms [Cd—O = 2.383 (6) and 2.414 (6) Å] from two 5‐carboxyimidazole‐4‐carboxylate ligands.     

Oxidative Coupling of Ge94‐ Zintl Anions ‐ Hexagonal Rod Packing of Linear [Ge9=Ge9=Ge9=Ge9]8‐

The compound [K(18‐crown‐6)]₈[Ge₉=Ge₉=Ge₉=Ge₉] ˙ 8en ( 1 ) featuring a [Ge₉=Ge₉=Ge₉=Ge₉]^8‐cluster anion was synthesized from K₄Ge₉ for the first time. The X‐ray single crystal analysis shows that, in many respects such as bond connection and packing style, compound 1 is quite different from the previously reported compounds [Rb(18‐crown‐6)]₈[Ge₉=Ge₉=Ge₉=Ge₉] ˙ 2en ( 2 ) and [Rb(18‐crown‐6)]₈[Ge₉=Ge₉=Ge₉=Ge₉] ˙ 6en ( 3 ). Crystal packing of 1 gives strong indications that the highly charged nano‐rods self assembly in a hexagonal rod packing.     

Linking Deltahedral Zintl Clusters with Conjugated Organic Building Blocks: Synthesis and Characterization of the Zintl Triad [R‐Ge9‐CHCHCHCH‐Ge9‐R]4−

The accessibility of triads with deltahedral Zintl clusters in analogy to fullerene–linker–fullerene triads is another example for the close relationship between fullerenes and Zintl clusters. The compound {[K(2.2.2‐crypt)]₄[RGe₉‐CH?CH? CH?CH‐Ge₉R]}(toluene)₂ (R=(2Z,4E)‐7‐amino‐5‐aza‐hepta‐2,4‐dien‐2‐yl), containing two deltahedral [Ge₉] clusters linked by a conjugated (1Z,3Z)‐buta‐1,3‐dien‐1,4‐diyl bridge, was synthesized through the reaction of 1,4‐bis(trimethylsilyl)butadiyne with K₄Ge₉ in ethylenediamine and crystallized after the addition of 2.2.2‐cryptand and toluene. The compound was characterized by single‐crystal structure analysis as well asNMR and IR spectroscopy.     

The σ‐Aromatic Clusters [Zn3]+ and [Zn2Cu]: Embryonic Brass

The triangular clusters [Zn₃Cp*₃]⁺ and [Zn₂CuCp*₃] were obtained by addition of the in situ generated, electrophilic, and isolobal species [ZnCp*]⁺ and [CuCp*] to Carmona’s compound, [Cp*Zn? ZnCp*], without splitting the Zn? Zn bond. The choice of non‐coordinating fluoroaromatic solvents was crucial. The bonding situations of the all‐hydrocarbon‐ligand‐protected clusters were investigated by quantum chemical calculations revealing a high degree of σ‐aromaticity similar to the triatomic hydrogen ion [H₃]⁺. The new species serve as molecular building units of Cu_nZn_m nanobrass clusters as indicated by LIFDI mass spectrometry.     

Extraction of Ternary Alloys: Synthesis and Crystal Structure of [K([2.2.2]crypt)]Cs7[Sn9]2(en)3

The compound [K([2.2.2]crypt)]Cs₇[Sn₉]₂(en)₃ ( 1 ) was synthesized from an alloy of formal composition KCs₂Sn₉ by dissolving in ethylenediamine (en) followed by the addition of [2.2.2]crypt and toluene. 1 crystallizes in the orthorhombic space group Pcca with a = 45.38(2), b = 9.092(4), c = 18.459(8) Å, and Z = 4. The structure consists of Cs₇[Sn₉]₂ layers which contain [Sn₉]^4– anions and Cs⁺ cations. The layers are separated by [K([2.2.2]crypt)]⁺ units. In the intermetallic slab (Cs₇[Sn₉]₂)^– compares the arrangement of pairs of symmetry‐related [Sn₉]^4– anions with the dimer ([Ge₉]–[Ge₉])^6– in [K([2.2.2]crypt)]₂Cs₄([Ge₉]–[Ge₉]), in which the clusters are linked by a cluster‐exo bond. The shortest distance between atoms of such two clusters in 1 is 4.762 Å, e. g. there are no exo Sn‐Sn bonds. The [Sn₉]^4– anion has almost perfect C_4v‐symmetry.     

Selenogermanate aus wäßriger Lösung: Darstellung und Struktur von Na4Ge2Se6 · 16 H2O

Selenogermanates from Aqueous Solution: Preparation and Structure of Na₄Ge₂Se₆ · 16 H₂O Selenogermanates(IV) are prepared from aqueous solutions by reaction of alkali selenides with GeSe₂. Na₄Ge₂Se₆ · 16 H₂O, being obtained from stoichiometric 1:1 quantities, is characterized by a complete X-ray structure analysis and by vibrational spectra. The compound is monoclinic (P2₁/c) with a = 9.894(4), b = 11.781(5), c = 12.225(6) Å, β = 92.90(4)°, Z = 2. It contains isolated Ge₂Se₆^4? anions consisting of two edge-sharing tetrahedra [Ge? Se 2.303(2)–2.419(2) Å] which are in contact to the hydrated octahedral [Na(H₂O)₆]⁺ ions through Se ? H? O bridges within an extensive hydrogen bridge system. Raman-active vibrations are observed at 306, 294, 207, 139, and 121 cm^?1. Adamantane-like Ge₄Se₁₀^4? can be prepared in a similar way as Ge₂Se₆^4? if a 1:2 molar ratio of alkali selenide to GeSe₂ is employed.