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.     

Two‐, One‐, and Zero‐Dimensional Elemental Nanostructures Based on Ge9‐Clusters

We investigated the structural principles of novel germanium modifications derived by oxidative coupling of Zintl‐type [Ge₉]^4?clusters in various ways. The structures, stabilities, and electronic properties of the predicted {²_∞[Ge₉]_n} sheet, {¹_∞[Ge₉]_n} nanotubes, and fullerene‐like {Ge₉}_n cages were studied by using quantum chemical methods. The polyhedral {Ge₉}_n cages are energetically comparable with bulk‐like nanostructures of the same size, in good agreement with previous experimental findings. Three‐dimensional structures derived from the structures of lower dimensionality are expected to shed light on the structural characteristics of the existing mesoporous Ge materials that possess promising optoelectronic properties. Furthermore, 3D networks derived from the polyhedral {Ge₉}_n cages lead to structures that are closely related to the well‐known LTA zeolite framework, suggesting further possibilities for deriving novel mesoporous modifications of germanium. Raman and IR spectra and simulated X‐ray diffraction patterns of the predicted materials are given to facilitate comparisons with experimental results. The studied novel germanium modifications are semiconducting, and several structure types possess noticeably larger band gaps than bulk α‐Ge.     

Synthesis of syn‐2,4‐Dimercapto‐1,3,2,4‐dithiadigermetane and Its Application to Ge2PdS4 Cluster Synthesis

The sulfurization of DmpGeH₃ (Dmp=2,6‐dimesitylphenyl) afforded the trinuclear germanium sulfide [DmpGe(μ‐S)]₂(μ‐S)₂Ge(SH)‐Dmp and a series of polythiadigermabicyclo[x.1.1]alkanes (x=3, 4, 5). The reduction of the S? S bonds of these germabicycloalkanes by NaBH₄ at 0 °C afforded the dinuclear mercaptogermane syn‐[DmpGe(SH)(μ‐S)₂Ge(SH)‐Dmp] ( 5 ) in good yield. The reaction of [Pd(dppe)Cl₂] (dppe=1,2‐bis(diphenylphosphanyl)ethane) and the dilithium salt of 5 prepared in situ by the addition of nBuLi (2 equiv) gave the Ge₂PdS₄ cluster [DmpGe(μ‐S)]₂[(μ‐S)₂Pd(dppe)], in which the dithiadigermetanedithiolate is bound to the Pd atom at the two thiolato sulfur atoms. The same reaction with [Pd(PPh₃)₂Cl₂] gave another Ge₂PdS₄ cluster, [DmpGe(μ‐S)]₂[(μ‐S)₂Pd(PPh₃)], but with the dithiadigermetanedithiolate and the Pd center conjoined through a μ‐S atom between the two germanium atoms in addition to the two thiolato sulfur atoms to form a highly distorted cluster core. The formation of two different types of Ge₂PdS₄ clusters represents the usefulness of 5 in the synthesis of various polynuclear complexes composed of germanium and transition metals.     

Reinvestigation of Ge4Se9 based on single‐crystal data

Tetra­germanium nona­selenide, Ge₄Se₉, adopts a two‐dimensional layered structure. The layer is made up of infinite chains of corner‐sharing GeSe₄ tetra­hedra and the chains are connected via the Ge₂Se₇ unit to form the two‐dimensional layer. These layers are stacked to form the three‐dimensional structure with a van der Waals gap. A previous structure report on Ge₄Se₉ based on powder diffraction data [Fjellvåg, Kongshaug & Stølen (2001). J. Chem. Soc. Dalton Trans. pp. 1043–1045] is comparable with our results except for the absolute structure determination.     

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.     

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.     

1,1‐Diethyl‐1‐germa‐2,3,4,5‐tetra‐tert‐butyl‐2,3,4,5‐tetraphospholan (C2H5)2Ge(tBuP)4, Molekül‐ und Kristallstruktur

1,1‐Diethyl‐1‐germa‐2,3,4,5‐tetra‐ tert ‐butyl‐2,3,4,5‐tetraphospholane (C₂H₅)₂Ge( t BuP)₄, Molecular and Crystal Structure The reaction of the diphosphide K₂[(tBuP)₄] · THF ( 1 ) with the germanium(IV) compound (C₂H₅)₂GeCl₂ leads via a [4 + 1]‐cyclo‐condensation reaction to 1,1‐diethyl‐1‐germa‐2,3,4,5‐tetra‐tert‐butyl‐2,3,4,5‐tetraphospholane (C₂H₅)₂Ge(tBuP)₄ ( 2 ) with the 5‐membered GeP₄ ring system. 2 could be characterized ³¹P NMR spectroscopically, mass spectrometrically and by a single crystal structure analysis.     

Molecular Precursors for the Phase‐Change Material Germanium‐Antimony‐Telluride,Ge2Sb2Te5 (GST)

This review provides an overview of the precursor chemistry that has been developed around the phase‐change material germanium‐antimony‐telluride, Ge₂Sb₂Te₅ (GST). Thin films of GST can be deposited by employing either chemical vapor deposition (CVD) or atomic layer deposition (ALD) techniques. In both cases, the success of the layer deposition crucially depends on the proper choice of suitable molecular precursors. Previously reported processes mainly relied on simple alkoxides, alkyls, amides and halides of germanium, antimony, and tellurium. More sophisticated precursor design provided a number of promising new aziridinides and guanidinates.     

Ge Pairs and Sb Ribbons in Rare‐Earth Germanium Antimonides RE12Ge7−xSb21 (RE=La–Pr)

The ternary rare‐earth germanium antimonides RE₁₂Ge_7?xSb₂₁ (RE=La–Pr; x=0.4–0.5) are synthesized by direct reactions of the elements. Single‐crystal X‐ray diffraction studies indicate that they adopt a new structure type (space group Immm, Z=2, a=4.3165(4)–4.2578(2) Å, b=15.2050(12)–14.9777(7) Å, c=34.443(3)–33.9376(16) Å in the progression from RE=La to Pr), integrating complex features found in RE₆Ge_5?xSb_11+x and RE₁₂Ga₄Sb₂₃. A three‐dimensional polyanionic framework, consisting of Ge pairs and Sb ribbons, outlines large channels occupied by columns of face‐sharing RE₆ trigonal prisms. These trigonal prisms are centered by additional Ge and Sb atoms to form GeSb₃ trigonal‐planar units. A bonding analysis attempted through a Zintl–Klemm approach suggests that full electron transfer from the RE atoms to the anionic substructure cannot be assumed. This is confirmed by band‐structure calculations, which also reveal the importance of Ge? Sb and Sb? Sb bonding. Magnetic measurements on Ce₁₂Ge_6.5Sb₂₁ indicate antiferromagnetic coupling but no long‐range ordering down to 2 K.