Germanium Anions Research Articles

Unusual nuclear exchange within a germanium-containing aromatic ring that results in germanium atom transfer

The delivery of single atoms is highly desirable for the straightforward synthesis of complex molecules, however this approach is limited by a lack of suitable atomic transfer reagents. Here, we report a germanium atom transfer reaction employing a germanium analogue of the phenyl anion. The reaction yields a germanium-substituted benzene, along with a germanium atom which can be transferred to other chemical species. The transfer of atomic germanium is demonstrated by the formation of well-defined germanium doped molecules. Furthermore, computational studies reveal that the reaction mechanism proceeds via the first example of an aromatic-to-aromatic nuclear germanium replacement reaction on the germabenzene ring. This unusual reaction pathway was further probed by the reaction of our aromatic germanium anion with a molecular silicon species, which selectively yielded the corresponding silicon-substituted benzene derivative.

Geometric evolution, electronic structure, and vibrational properties of ScGen− (n = 6–17) anion clusters: A DFT insight

AbstractA comparison of theoretical and experimental properties is the most effective strategy for determining the global minimum (GM) because there is no experimental method to directly test the GM structure of clusters by now. The molecular and electronic structures and properties of Sc‐doped germanium anion clusters were explored via quantum chemistry calculations using mPW2PLYP scheme and unprejudiced structural searching technique ABCluster. Isomers are determined by ABCluster structural searches, followed by reoptimization of a great number of candidate geometries. The simulated photoelectron spectra for the GM structures match with those measured in experiment, suggesting that the current most stable structures are existence in the experiment. The molecular structural evolution modes appear as follows: as the cluster size n increases, the growth patterns are from the Sc‐linked geometry (n = 10, 11) in which the Sc atom acts as a linker (Sc atom connects two Ge sub‐clusters) to the Sc‐encapsulated form (n = 13–17) in which the Sc atom is settled in the core of the Ge‐cage framework. Besides, the properties including stability, HOMO‐LUMO gap, charge transfer, IR, Raman, and UV–Vis spectra were calculated. The Raman spectra are red‐shifted from the Sc‐linked to Sc‐encapsulated configurations. The analyses of stability, HOMO‐LUMO gap, and UV–Vis spectra revealed that the ScGe16− nanocluster could be the most suitable building block for further development as potential optoelectronic materials such as solar cell.

Structural Evolution, Electronic Structures, and Vibrational Properties of Anionic LuGen (n = 5-17) Clusters: From Lu-Linked to Lu-Encapsulated Configurations.

The structural evolution pattern and electronic properties of Lu-doped germanium anion clusters, LuGen- (n = 5-17), have been investigated using a global search method combined with a double hybrid density functional theory and by comparing the theoretical PES spectra with the experimental ones. It is found that, for the structural growth patterns, a Lu-linked configuration is preferred for n = 10-14 in which the Lu atom as a linker connects two Ge subclusters and a Lu-encapsulated Ge cage-like motif is preferred for n = 15-17. The simulated PES spectra agree with experimental ones, revealing that the current global minimum structures are the true minima. The properties such as relative stability, charge transfer, highest-energy occupied molecular orbital-lowest-energy unoccupied molecular orbital (HOMO-LUMO) gap, IR, Raman, and ultraviolet-visible (UV-vis) spectra have been evaluated. The results of IR and Raman spectra could provide additional ways to experimentally identify the structure of these clusters. The results of stability, HOMO-LUMO gap, and UV-vis spectra could make the LuGe16- cluster the most suitable building block for further development as a potential optoelectronic material.

ChemInform Abstract: Potassium, Cesium, and Ammonium Peroxogermanates with Inorganic Hexanuclear Peroxo Bridged Germanium Anion Isolated from Aqueous Solution.

AbstractK6 [Ge6(μ‐O2)6(μ‐O)6 (OH)6]·14H2O (I), Cs4.2(NH4)1.8 [Ge6(μ‐O2)6(μ‐O)6 (OH)6]·8H2O (II), and K2.4(NH4)3.6 [Ge6(μ‐O2)6(μ‐O)6 (OH)6]·6H2O (III) are isolated from K or Cs hydroxogermanate solutions by addition of aq.

Potassium, Cesium, and Ammonium Peroxogermanates with Inorganic Hexanuclear Peroxo Bridged Germanium Anion Isolated from Aqueous Solution.

Potassium (K6[Ge6(μ-OO)6(μ-O)6(OH)6]·14H2O, 1), cesium ammonium (Cs4.2(NH4)1.8[Ge6(μ-OO)6(μ-O)6(OH)6]·8H2O, 2), and potassium ammonium (K2.4(NH4)3.6[Ge6(μ-OO)6(μ-O)6(OH)6]·6H2O, 3) peroxogermanates were isolated from 3% hydrogen peroxide aqueous solutions of the corresponding hydroxogermanates and characterized by single crystal and powder X-ray diffraction studies and by Raman spectroscopy and thermal analysis. The crystal structure of all three compounds consists of cations of potassium and/or ammonium and cesium, water molecules, and centrosymmetric hexanuclear peroxogermanate anion [Ge6(μ-OO)6(μ-O)6(OH)6](6-) with six μ-oxo- and six μ-peroxo groups. Peroxogermanates demonstrate relatively high thermal stability: the peroxide remains in the structure even after water release after heating to 100-120 °C. DFT calculations of the peroxogermanate [Ge6(μ-OO)6(μ-O)6(OH)6](6-) anion confirm its higher thermodynamic stability compared to the hydroperoxo- and oxogermanate analogues.

Evidence of a Mixed Magnetic Phase in EuMgGe: A Semi­metallic Zintl Compound with TiNiSi Structure Type

AbstractThe ternary Zintl phase EuMgGe was synthesized from the elements, and its structure solved by single‐crystal X‐ray diffraction. Chemical bonding is discussed, by means of electronic structure calculations at the DFT level and its physical properties characterized with respect to electronic conductivity, magnetic susceptibility, specific heat capacity, and magnetoresistivity. The compound may be interpreted according to the Zintl‐Klemm concept as (Eu2+)(Mg2+)(Ge4–) with isolated germanium anions. Resistivity measurements reveal a semimetallic character, which is consistent with the vanishing energy gap obtained from our calculations. The magnetic susceptibility and the specific heat indicate that two consecutive transitions take place, at 9 and 16 K, and they show evidence of magnetic frustration. A possible physical scenario for this magnetic behavior is discussed based on known models of partially frustrated magnets.

Synthetic Access to a Hydrocarbon-Soluble Trifluorinated Ge(II) Compound and its Sn(II) Congener

Trifluorinated germanium anions attracted attention of theoretical chemists already in the late 1990s to predict their physical and chemical properties. However these species were not synthesized in the laboratory, although substantial evidence for their existence was obtained from the mass spectrometry of GeF4. The present study shows that controlled fluorination of LMNMe2 (L = PhC(N(t)Bu)2, M = Ge, Sn) using HF·pyridine in toluene leads to the formation of [LH2](+)[MF3](-) under elimination of HNMe2. The products contain the trifluorinated Ge(II) and Sn(II) anionic species which are stabilized by interionic H···F bonds. The new compounds were characterized by single crystal X-ray structural analysis, NMR spectroscopy, and elemental analysis.

Synthesis, Crystal, and Electronic Structure of the New Ternary Zintl Phase Eu2–xMg2–yGe3 (x = 0.1; y = 0.5)

AbstractThe new ternary phase Eu2–xMg2–yGe3 (x = 0.1, y = 0.5) was obtained by solid‐state synthesis and the structure determined by means of Single Crystal X‐ray Diffraction. The compound crystallizes with the orthorhombic space group Cmcm (no. 63) having structural features of the low‐temperature modification of LaSi. The crystal structure contains two different types of germanium anions: isolated Ge4– and $\rm^{2}_{\infty}$[Ge2–x–y] chains. The cation substructure is partially disordered and is best represented assuming a split position. The chemical bonding is well represented by the Zintl‐Klemm concept. Resistivity measurements reveal that the compound is metallic. DFT band structure calculations were carried out on the ideal stoichiometric compound Eu2Mg2Ge3, showing that this model (x = 0; y = 0) would be also metallic as a consequence of the ecliptic stacking of anions. Susceptibility and specific heat measurements evidence the presence of weak, and probably frustrated, antiferromagnetic interactions between disordered europium atoms.

Hyperbranched perfluorinated poly(phenylene germanes) obtained by polycondensation of A2B2 and AB3 monomers

AbstractA set of new hyperbranched (HB) perfluorinated poly(phenylene germanes) PPGs, whose connectivity is supported by germanium atoms, was synthesized via an activated copolycondensation of AB3, HGe(C6F5)3 and A2B2, H2Ge(C6F5)2 monomers. Light scattering showed that the content of the AB3 and A2B2 reagents and the sequence of their activation affect the molecular mass and the conformation of PPGs. Morphology of the subaggregates, examined with scanning electron microscopy (SEM) at different magnifications, demonstrated their fractal structure. The conformations of individual PPG macromolecules, obtained with light scattering, were in accord with the morphology of the subaggregates observed with SEM. This allowed to conclude that the fractal approach can be applied up to the scale of the self‐assembly of dendrons during the reaction. The branching structure was analyzed with 19F nuclear magnetic resonance (NMR). The chemical shifts of the main‐chain fluorines depended on the proximity of the C6F4 links to the germanium anion because of the redistribution of the germanium anion charge along the branches via σ–π conjugation. The interdendron links are due to the knots originating from the A2B2 monomer, since they contain nonreacted hydrogens. The interdendron links increase the molecular mass of the copolymers with respect to that of the AB3 homopolymer whose molecular mass cut‐off is due to the entrapment of the focal ion pair. Copyright © 2010 John Wiley & Sons, Ltd.

Accumulation and Reaction of Electrochemically Generated Carbon and Germanium Anions

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Chemical composition analysis of germanate glass by alkalimetric titration of germanate mannitol complex

A titrimetric method has been developed for the determination of germanium in glass. Germanium anion in aqueous solution combine with two molecules of mannitol to form a germanate mannitol complex in presence of sufficient mannitol. The complex is moderately strong acid and germanium can be determined by alkalimetric titration. The proposed method is simple, rapid and selective and the method is successfully applied for the determination of germanium in glass.

Cocatalysis in phase-transfer catalyzed fluorination of alkyl halides and sulfonates

Phase-transfer catalyzed (PTC) fluorination of alkyl halides and sulfonates with solid KF proceeds efficiently when cocatalyst triphenyltin fluoride is used. The cocatalytic action of the tin compound consists in continuous formation of difluorotriphenylstannate anion that as the tetraalkyloammonium salt enter the solution where it reacts with alkyl halides to produce alkyl fluorides. The cocatalytic system was used to synthesis of 1,1-difluoroalkanes in two steps from aldehydes. A new kind of PTC was elaborated in which Ph 3SnF acts as phase transfer catalyst via continuous formation of potassium salts of diflurotriphenylstannate anions soluble in dipolar aprotic solvents. A new, simple and general method of synthesis of tetraalkylammonium and potassium salts of difluorotriorgano-tin, silicon and germanium anions is reported.

The Role of Sequestering Agents in the Formation and Structure of Germanium Anion Cluster Polymers.

AbstractFor Abstract see ChemInform Abstract in Full Text.

The role of sequestering agents in the formation and structure of germanium anion cluster polymers.

Large blue-green, transparent crystalline needles of [K-(2,2)diaza-[18]-crown-6]KGe(9).3en are prepared, in high yield, from the reaction of (2,2)diaza[18]-crown-6 in toluene with a solution of "KGe(4)" in ethylenediamine (en). The compound crystallizes in the orthorhombic space group Pnma (a = 10.9763(12) A, b = 27.265(3) A, c = 13.880(1) A; Z = 4). The crystal structure of [K-(2,2)diaza-[18]-crown-6]KGe(9).2en features one-dimensional [KGe(9)](-) bare intermetallic chains formed from the linking, via exo-bonds, of nido-Ge(9)(2-) clusters. Uncomplexed K atoms effectively cap the square bases of the monocapped square antiprismatic [Ge(9)](2-) clusters. The optical band gap of the title compound is 1.25 eV. The use of weaker sequestering agents in the isolation of Ge cluster anions from en solutions provides an additional handle in a controlled molecular route to preparing new low-dimensional Zintl phases.

The effect of substituents on the structure and reactivity of organogermanium anions

The replacement of the ethyl group in Et 3GeH by a phenyl group was shown by equilibrium metallation to halve the p K a value compared with analogous CH acids. NMR showed that the decreased acceptor effect of the phenyl group in the PhEt 2Ge − anion is caused by a considerably reduced contribution of the mesomeric effect to anion stabilization compared with what happens in the corresponding carbanions. At the same time, the stabilization of the organogermanium anion increases the role of π-polarization of the aromatic substituent and this contribution is comparable with the mesomeric effect value. A stabilizing effect of organosilicon and organogermanium substituents due to a high degree of polarizability has been shown by concurrent methanolysis of Et 3GeLi and REt 2GeLi (R = Me 3Si, Et 3Si, Me 3Ge, Et 3Ge, t-Bu, Ph). An unexpected reaction of the trimethylsilyl anion with the Me 3SiGeEt − 2 anion leading to diethylgermane dianion, Et 2Ge 2− has been revealed. The existence of this process supports the suggested absence of ( d–p)π interaction in germanium anions with organo-silicon and -germanium substituents.