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Matrix isolation infrared spectroscopy combined with quantum-chemical calculations were employed to study the reactions of calcium atoms with silane, germane, and stannane in a 4 K argon matrix. The ion pairs [HCa]+ and [EH3]- (E = Si, Ge, and Sn) in both the classical structure HCaEH3 and the bridged structure HCa(μ-H)3E were identified based on the H/D isotopic substitution experiments and quantum-chemical calculations. The results show that the reaction between ground-state Ca and EH4 proceeds inefficiently, and only after the photolytic activation of Ca atoms to the Ca(1P:4s4p) state does insertion occur to give HCaEH3, which rearranges to HCa(μ-H)3E upon photolysis. Topological analysis of the electronic structure suggests that the nonclassical structure HCa(μ-H)3E is formed by the electrostatic interaction with charge-inverted hydrogen bridge bond, while HCaEH3 is dominated by (HCa)+(EH3)- ion pair interactions.

The synthesis of a variety of bis(catecholato)germanes is reported. The Lewis acidity of the bis(catecholato)germanes was assessed using the experimental Gutmann–Beckett method and computational FIA and GEI methods. The oligomerization of alkenes using bis(catecholato)germanes demonstrates the use of these complexes in catalysis. The use of donor additives in the dimerization of α-methylstyrene resulted in selectivity control comparable to transition metal catalyst systems.

The intra- and inter molecular inter-ring η 6 ⇌ η 6 -haptotropic rearrangements (IRHR), occurring by involving interactions to Ge atoms in arylgermanes, were investigated theoretically and experimentally. The new methods for the synthesis of non-symmetrical polyaromatic Ge compounds were elaborated. Digermane Ph 3 GeGeMe 2 Cl ( 2 ) was obtained from Ph 3 GeGeMe 2 NMe 2 ( 1 ) under action of Me 3 SiCl. Aryl digermane Ph 3 GeGeMe 2 (η 6 -C 6 H 5 )Cr(CO) 3 ( 4 ) was obtained after lithiation of (η 6 -C 6 H 6 )Cr(CO) 3 ( 3 ) with subsequent interaction with 2 . It was established that thermally induced intra molecular IRHR in 4 is not observed experimentally; at similar reaction conditions in the presence of tetralin C 10 H 12 ( 7 ) the bimolecular inter molecular IRHR occurs giving (η 6 -C 10 H 12 )Cr(CO) 3 ( 8 ). DFT analysis of the intra molecular IRHRs for model germane ( p -Tol) 2 Ge(H)(η 6 -Tol- p )Cr(CO) 3 ( MC1 ) and digermane Ph 3 GeGeH 2 (η 6 -Ph)Cr(CO) 3 ( MC2 ) indicates a plausible effect of 3c-2e (agostic) Ge–H···Cr interaction on success of such rearrangement. The theoretical activation barrier is determined to be in the range of 35–37 kcal/mol. The model compound (η 6 -C 6 H 3 (GeHPh 2 )Me 2 - p )Cr(CO) 3 ( 12 ) was obtained from (η 6 -C 6 H 4 Me 2 - p )Cr(CO) 3 ( 11 ). The decomposition of 12 was observed under conditions of thermally induced IRHR. Molecular structures of 8 , 11 and 12 in a crystal were investigated by XRD.

The selective activation of C Cl bonds of hydrochlorofluoromethanes and chloromethanes at moderate reaction conditions using ACF in a combination with Et 3 GeH is presented. The reactions of the chloromethanes (CH 3 Cl, CH 2 Cl 2 , CHCl 3 and CCl 4 ) in the presence of Et 3 GeH and ACF as catalyst led to the activation of only one C Cl bond resulting in the hydrodechlorination. Friedel-Crafts reactions with benzene as solvent are suppressed by Et 3 GeH. A selective hydrodechlorination of hydrochlorofluoromethanes was achieved, because a transformation of a C F bond into a C H bond by the combination of ACF with Et 3 GeH did not occur. Supporting Pulse TA ® experiments illustrated the interaction between the solid catalyst and Et 3 GeH, the solvent benzene or CH 2 Cl 2 .

Chemical Vapor Deposition delivers an atomic element into a solid phase via a gas phase. In such context, knowledge of the vapor – solid distribution of the elements is key. But CVD is a notorious non-equilibrium process. Notwithstanding the non-equilibrium, an analysis of silicon germanium chemical vapor deposition, via silane and germane, is conducted with classical thermodynamics for a complete determination of the vapor – solid distribution. And a theory assuming a heterogeneous chemical equilibrium is developed. The knowledge of two linear functions is enough for accessing a distribution which is then determined over the full range of composition, without any major difficulty. Reduced pressure chemical vapor deposition and ultra-high vacuum chemical vapor deposition vapor – solid distributions are also reconciled within the same conceptual framework. The impact of the pressure, and of silicon precursors are neatly clarified. The underlying laws necessary for the determination of Si1-xGex vapor - solid distributions are thus completely known. VS distributions of binary alloys such as Si:B, Si:P and Ge1-xSnx, are also inferred to experience similar chemical equilibria.

The impurity composition of 28SiH4, 29SiH4, and 30SiH4 silanes and 72GeH4, 73GeH4, 74GeH4, and 76GeH4 germanes isotopically enriched to above 99.9 at % has been studied by gas chromatography/mass spectrometry using capillary adsorption columns. Impurities have been identified by comparing their mass spectra with NIST data and information available in the literature, and by inferring their structure from fragment ions and retention times. We have identified 53 impurity substances in silanes and 42 in germanes: permanent gases; saturated, unsaturated, halogen-containing, and aromatic C1–C9 hydrocarbons; their homologues; alkyl derivatives of silane and germane; chlorogermane; siloxanes; fluorosiloxanes; sulfur compounds; and dioxane. The silicon- and germanium-containing impurities have been shown to be isotopically enriched, as the major component. The detection limits of the impurities are 5 × 10–8 to 3 × 10–5 vol %, comparing well with the best results in the literature.

This study was focused on elucidating the origin of the catalytic activity displayed by non-precious-metal-based oxygen reduction reaction (ORR) catalysts before and after heat treatment. Electrochemical measurements were recorded using a series of metal phthalocyanines calculated to exhibit varying oxygen adsorption energies before and after heat treatment at a temperature sufficiently high to facilitate degradation. Collectively, the results indicate that while the oxygen adsorption is germane to the catalytic activity before heat treatment, the ORR appears to proceed through a different pathway that is not dependent on adsorption energy after heat treatment. These conclusions help to explain the high catalytic activities exhibited by carbon- or nitrogen-based materials containing metal ions after heat treatment and may lead to the realization of substitutes for ORR catalysts that utilize precious transition metals.

The reaction of the germane [Ge(H)(2-C6H4PPh2)3] (1) and the platinum precursor complex [Pt(nbe)3] (nbe = norbornene) gave a racemic mixture of the germyl complex [Pt(nor){Ge(2-C6H4PPh2)3}] (2; nor = exo-2-norbornyl, exo-2-bicyclo[2.2.1]heptyl). Mechanistic studies showed that the hydrido complex [Pt(H){Ge(2-C6H4PPh2)3}] (3) is not formed as an intermediate during the formation of 2. Further studies revealed that in contrast to the chlorido complex [Pt(Cl){Ge(2-C6H4PPh2)3}] (4), the methyl compound [Pt(CH3){Ge(2-C6H4PPh2)3}] (5) is an efficient starting compound for accessing cationic platinum species. Complex 5 was converted into the triflato complex [Pt(OTf){Ge(2-C6H4PPh2)3}] (6) as well as the complexes [Pt(L){Ge(2-C6H4PPh2)3}][B{3,5-C6H3(CF3)2}4] [L = thf (7), toluene (8), CH2Cl2 (9), PPh3 (10)].

Tristrimethylsilylgermane, (Me3Si)3GeH, was employed as a molecular model compound for hydrogen terminated Ge(111) surfaces. Time and temperature dependent NMR spectroscopy yielded rate constants for the reaction between (Me3Si)3GeH and elemental sulfur and allowed for the determination of the activation energy for this molecular model reaction to mimic germanium surface passivation.

We have studied the very low temperature epitaxy of pure Ge and of Ge-rich SiGe alloys in a 200 mm industrial reduced pressure chemical vapour deposition tool. We have, first of all, benchmarked germane (GeH 4 ) and digermane (Ge 2 H 6 ) for the growth of pure Ge. Used Ge 2 H 6 instead of GeH 4 enabled us to dramatically increase the Ge growth rate at temperatures 425 °C and lower (5.6 nm min −1 compared to 0.14 nm min −1 at 350 °C with a Ge 2 H 6 mass-flow one fourth that of GeH 4 ). We have also evaluated at 400 °C, 100 Torr, the impact of the GeH 4 or Ge 2 H 6 mass-flow on the Ge growth rate. For a given Ge atomic flow, the higher surface reactivity of digermane yielded roughly five times higher growth rates than with germane. We have then combined digermane with disilane (Si 2 H 6 ) or dichlorosilane (SiH 2 Cl 2 ) in order to study the GeSi growth kinetics at 475 °C, 100 Torr. While the SiH 2 Cl 2 mass-flow did not have any clear influence on the GeSi growth rate (with a 14 nm min −1 mean value, then), a Si 2 H 6 mass-flow increase resulted in a slight GeSi growth rate increase (from 11 nm min −1 up to 14 nm min −1 ). Significantly higher Ge concentrations were otherwise accessed with dichlorosilane than with disilane, in the 77–82% range compared to the 39–53% range, respectively.

Photochemical reactions of germane and diphenylgermane with Ru(PP) 2 H 2 (PP = R 2 PCH 2 CH 2 PR 2 or DuPhos, R = Ph dppe, R = Et depe, R = Me dmpe) are reported. Reaction with GeH 4 generates a mixture of cis and trans isomers of Ru(PP) 2 (GeH 3 )H except for the DuPhos complex which yields the product only in the cis form. In situ laser photolysis (355 nm) demonstrates that the initial product is the cis isomer that undergoes thermal isomerization to the trans isomer. The complex cis-[Ru(dppe) 2 (GeH 3 )H] crystallizes selectively, allowing determination of its X-ray structure as a germyl hydride with a long Ru-H···Ge separation of 2.64(3) Å indicating that no residual interaction between the RuH and Ge is present. DFT calculations are also consistent with full oxidative addition. The structure of cis-[Ru(DuPhos) 2 (GeH 3 )H] reveals significant distortion from an octahedral geometry. The major species in the crystal (95%) exhibits a structure with a Ru-H···Ge distance of 2.42(5) Å suggesting negligible interaction between these centers. DFT calculations of the structure are consistent with the experimental determination. The reactions of Ru(PP) 2 H 2 with diphenylgermane yield cis-[Ru(PP) 2 (GePh 2 H)H] exclusively for PP = dmpe and depe, while the cis isomer is dominant in the case of dppe. A photochemical competition reaction between Ru(dppe) 2 (H) 2 and the two substrates Ph 2 SiH 2 and Ph 2 GeH 2 results in both Si-H and Ge-H oxidative addition activation with a kinetic preference (0.18:1) for the germyl hydride product. Thermal conversion of Ru(dppe) 2 (SiPh 2 H)H to Ru(dppe) 2 (GePh 2 H)H is observed on heating.

Specific features of the pyrolysis of hydride molecules on the surface of a Si1–x Ge x film under conditions of epitaxial film deposition of a mixture of silicon and germanium hydrides have been studied. Temperature dependences of the kinetic coefficients responsible for the rate of hydrogen desorption from the Si1–x Ge x film surface and the rate of dissociation of gas molecule radicals adsorbed by the surface of the growing film have been obtained for the first time, using the developed kinetic models of surface pyrolysis and the results of engineering experiments in the temperature range 450–800°C. A correlation between the dissociation frequencies of silane and germane molecules, as well as a correlation of the dissociation frequencies with other kinetic parameters of the system were revealed.

The impurity composition of germane has been studied by gas chromatography/mass spectrometry. We have determined permanent gases, C1–C9 hydrocarbons, fluorine- and chlorine-containing and aromatic hydrocarbons, ethers, hydrogen sulfide, germane homologs, alkyl derivatives of germane, and chlorogermane. The content of some impurities in high-pure germane is 2 × 10–6 to 1 × 10–3 vol %. The detection limits for impurities lie in the range 4 × 10–8 to 5 × 10–5 vol %.

The paper considers two main approaches discussed in literature for conversion of gaseous fluorides SiF4, GeF4 and hydrogen-containing compound of germanium, i.e., GeH4, isotopic enriched by centrifugal method, into target products—stable isotopes of silicon and germanium in the form of bulk polycrystals and thin layers. In the first two-step (chemical) approach the fluorides are converted into intermediate compounds which are further subjected either to pyrolysis or to reduction by hydrogen. In the second single-step (plasma-chemical) approach the gaseous fluorides are reduced by hydrogen in plasma sustained by the discharges of different types.

Amorphous germanium carbides have been prepared by X-ray activated Chemical Vapor Deposition from germane/allene systems. The allene percentage and irradiation time (total dose) were correlated to the composition, the structural features, and the optical coefficients of the films, as studied by IR and UV-VIS spectroscopic techniques. The materials composition is found to change depending on both the allene percentage in the mixture and the irradiation time. IR spectroscopy results indicate that the solids consist of randomly bound networks of carbon and germanium atoms with hydrogen atoms terminating all the dangling bonds. Moreover, the elemental analysis results, the absence of both unsaturated bonds and CH3 groups into the solids and the absence of allene autocondensation reactions products, indicate that polymerization reactions leading to mixed species, containing Ge-C bonds, are favored. Eopt values around 3.5 eV have been found in most of the cases, and are correlated with C sp3-bonding configuration. The B1/2 value, related to the order degree, has been found to be dependent on solid composition, atoms distribution in the material and hydrogenation degree of carbon atoms.

Reactions of group 11 metal chlorides (CuCl, AgCl, AuCl) with {(o-Ph2P)C6H4}3E(F) (E = Si (1), Ge (2), Sn (3)) provide a complete series of metallasilatrane [{(o-Ph2P)C6H4}3(F)Si]MCl (E = Cu (4), Ag (5), Au (6)), metallagermatrane [{(o-Ph2P)C6H4}3(F)Ge]MCl (E = Cu (7), Ag (8), Au (9)), and metallastannatrane [{(o-Ph2P)C6H4}3(F)Sn]MCl (E = Cu (10), Ag (11), Au (12)) complexes. Structural analyses clearly show the presence of M→E interactions in all of these complexes and establish the presence of periodicity; heavier group 14 elements E act as stronger electron acceptor ligands, and heavier group 11 metals exhibit higher donor ability toward ER4. Density functional theory calculations fully support these trends and suggest that σ-acceptor ability of saturated (four-coordinate) heavier group 14 element compounds toward group 11 metals is related to σ*(E–F) molecular orbital levels, which mainly depend on the deviation of the geometry around E from tetrahedral geometry to trigonal bipyramidal.

Determining Ge isotopic compositions of sulfides is important to understand the ore-forming processes. Single step anion-exchange chromatography was previously used to recover Ge from silicates and lignites. We apply this procedure to recover Ge from sulfides before determining Ge isotopic compositions by hydride generation (HG)-MC-ICP-MS. Germanium is quantitatively recovered by the proposed sample preparation method. There are no obvious isotope biases for Ge-bearing solutions containing significant amounts of Cu, Sn, and W. However, δ 74 Ge values show obvious shifts if the solutions contain high Zn, Pb, and Sb, which is possibly attributed to suppression of germane formation that fractionates Ge isotopes. The long-term reproducibility for Ge standard solution is about ± 0.18‰ for δ 74 Ge. Spex and Merck standard solutions yield mean δ 74 Ge values of − 0.70 ± 0.19‰ and − 0.36 ± 0.08‰, respectively. The calculated δ 74 Ge value (− 5.13‰) of sphalerite standard based on doping experiments is indistinguishable from those of sphalerite without doping (− 5.05‰ and − 5.01‰). Sulfides from the Jinding, Shanshulin, and Tianqiao Pb–Zn deposits in SW China have δ 74 Ge values of − 4.94‰ to + 2.07‰. The paragenetic sequence of sulfides from the Shanshulin and Tianqiao Pb–Zn deposits is pyrite, sphalerite and galena from early to late. Sulfides from the same ore show a trend of δ 74 Ge pyrite 74 Ge sphalerite 74 Ge galena , which may be controlled by the kinetic or Rayleigh fractionation.

The heats of formation of alkyl-substituted XH4 (X = C, Si, Ge, Sn, Pb) molecular ions have often never been measured or are not known to better than 10 or 20 kJ/mol. The present study on these Main Group IV compounds adopts a graphical approach that relates cation heats of formation to cation size. A study of methyl substitution in XH4 is followed by a similar examination of heat of formation data on ethyl substitution in methane, silane, germane, stannane, and plumbane. The results provide tests of the validity of this graphical method as well as its use as a predictive tool for determining cation and neutral heats of formation. Suggestions are made of the need to investigate or reinvestigate the ionization energies and/or the heats of formation of several of the molecules studied. Results and conclusions are tabulated.

Structural studies were performed on heptacoordinate compounds of silicon {(o-Ph2P)C6H4}3SiX (X = F (1), Cl (3), H (5)) and germanium {(o-Ph2P)C6H4}3GeX (X = F (2), Cl (4), H (6), Me (7)) compounds featuring three phosphine donors. We found that 5, 6, and 7 have approximately a C3 symmetry similar to Corriu’s compounds (heptacoordinate silane {(o-Me2NCH2)C6H4}3SiX (X = F (8), H) and germane {(o-Me2NCH2)C6H4}3GeX (X = H, F) with three nitrogen donors coordinating to the central Si/Ge trans to the Cipso atoms). In contrast, the Si compounds 1 and 3 and the Ge compounds 2 and 4 have novel heptacoordinate geometries; the incorporation of such electronegative substituents as F and Cl results in the change of one phosphine donor from the position trans to the Cipso atom to that trans to the X atom. Compounds 1–4 retain this unprecedented geometry in solution but show dynamic behavior. The structural modification observed upon changing the substituent at Si and Ge is rationalized by electrostatic and charge tran...

Metal-catalysed CO2 hydrogenation is considered a source of methane in serpentinized (hydrated) igneous rocks and a fundamental abiotic process germane to the origin of life. Iron, nickel, chromium and cobalt are the catalysts typically employed in hydrothermal simulation experiments to obtain methane at temperatures >200°C. However, land-based present-day serpentinization and abiotic gas apparently develop below 100°C, down to approximately 40–50°C. Here, we document considerable methane production in thirteen CO2 hydrogenation experiments performed in a closed dry system, from 20 to 90°C and atmospheric pressure, over 0.9–122 days, using concentrations of non-pretreated ruthenium equivalent to those occurring in chromitites in ophiolites or igneous complexes (from 0.4 to 76 mg of Ru, equivalent to the amount occurring approximately in 0.4–760 kg of chromitite). Methane production increased with time and temperature, reaching approximately 87 mg CH4 per gram of Ru after 30 days (2.9 mgCH4/gru/day) at 90°C. At room temperature, CH4 production rate was approximately three orders of magnitude lower (0.003 mgCH4/gru/day). We report the first stable carbon and hydrogen isotope ratios of abiotic CH4 generated below 100°C. Using initial δ13CCO2 of -40‰, we obtained room temperature δ13CCH4 values as 13C depleted as −142‰. With time and temperature, the C-isotope separation between CO2 and CH4 decreased significantly and the final δ13CCH4 values approached that of initial δ13CCO2. The presence of minor amounts of C2-C6 hydrocarbons is consistent with observations in natural settings. Comparative experiments at the same temperatures with iron and nichel catalysts did not generate CH4. Ru-enriched chromitites could potentially generate methane at low temperatures on Earth and on other planets.

The germane [Ge(H)(2-C6H4PPh2)3] (2) was synthesized by reaction of Li[Ge(2-C6H4PPh2)3] (1) with water. The presence of nBuBr led to the formation of [Ge(nBu)(2-C6H4PPh2)3] (3). The complex [Ru(Cl){Ge(2-C6H4PPh2)3}] (4) was obtained by reaction of 2 with [Ru(Cl)2(PPh3)3] and NEt3. The ruthenium-bound Ge(2-C6H4PPh2)3 moiety in 4 can be converted into a Ge(Cl)(2-C6H4PPh2)2 fragment on treatment of 4 with a solution of HCl in diethyl ether to yield [Ru(Cl){Ge(Cl)(2-C6H4PPh2)2}(PPh3)] (5). The reaction of complex 4 with potassium hydride in an atmosphere of dihydrogen led to [Ru{Ge(2-C6H4PPh2)3}(H)(H2)] (6). Complex 6 reacted with hydrazine to give [Ru{Ge(2-C6H4PPh2)3}(H)(N2H4)] (7). With an excess of hydrazine, complex 6 catalyzed the disproportionation of hydrazine to produce ammonia and the ruthenium complex [Ru{Ge(2-C6H4PPh2)3}(H)(NH3)] (8).

We have studied the in-situ boron (B) doping of germanium (Ge) and silicon (Si) in Reduced Pressure-Chemical Vapor Deposition. Three growth temperatures have been investigated for the B-doping of Ge: 400, 600 and 750 °C at a constant growth pressure of 13300 Pa (i.e. 100 Torr). The B concentration in the Ge:B epilayer increases linearly with the diborane concentration in the gaseous phase. Single-crystalline Ge:B layers with B concentrations in-between 9 ∙ 1017 and 1 ∙ 1020 cm− 3 were achieved. For the in-situ B doping of Si at 850 °C, two dichlorosilane mass flow ratios (MFR) have been assessed: F[SiH2Cl2]/F[H2] = 0.0025 and F[SiH2Cl2]/F[H2] = 0.0113 at a growth pressure of 2660 Pa (i.e. 20 Torr). Linear boron incorporation with the diborane concentration in the gas phase has been observed and doping levels in-between 3.5 ∙ 1017 and 1 ∙ 1020 cm− 3 were achieved. We almost kept the same ratio of B versus Si atoms in the gas phase and in the Si epilayer. By contrast, roughly half of the B atoms present in the gas phase were incorporated in the Ge:B layers irrespective of the growth temperature. X-Ray Diffraction (XRD) allowed us to extract from the angular position of the Ge:B layer diffraction peak the substitutional B concentration. Values close to the B concentrations obtained by 4-probe resistivity measurements were obtained. Ge:B layers were smooth (

Spirogermabifluorene (C24H16Ge, 1) and the anionic products of its reduction with alkali metals were prepared and investigated by single-crystal X-ray diffraction. A monoanionic intermediate product of the reduction, formed upon the cleavage of a Ge–C bond and proton abstraction from the solvent, was isolated in the form of the cesium salt, [Cs+(diglyme)(C12H8GeC12H9−)] (2). Structural investigation of 2 revealed the presence of a tricoordinated germanium center and complexation of the cesium cation by two aromatic moieties. The reduction of 1 with an excess of alkali metals leads to the cleavage of the second Ge–C bond with subsequent elimination of biphenyl to give the C12H8Ge2− dianion which was crystallized as the sodium adduct, [{Na+(THF)}2(C12H8Ge2−)] (3). The structural elucidation for complex 3 shows η3- and η5-coordinations of the sodium ions to the π-system of dianions. The resulting Na⋯C and Na⋯Ge contacts along with the Na⋯OTHF interactions lead to the formation of the zigzag polymeric chains in the crystal lattice of 3.

In heptane solvent, Ru3(CO)12 reacts with tertiary butyl germane at reflux, to afford six new bimetallic ruthenium–germanium carbonyl cluster complexes Ru3(CO)9(μ3-GetBu)2, 1, Ru2(CO)6(μ-GetBuH)3, 2, Ru4(CO)10(μ4-Ge2tBu2)(μ-GetBuH)2, 3, Ru4(CO)8(μ4-Ge2tBu2)(μ-GetBuH)2(μ3-GetBu)(H), 4, Ru5(CO)12(μ3-GetBu)2(μ4-GetBu)(H), 5, Ru6(CO)12(μ3-GetBu)4(H)2, 6. Complex 2 was obtained as a result of cluster fragmentation while cluster condensation provided higher nuclearity ruthenium–germanium complexes 3–6 with varying Ru–Ge ratios. All six compounds were structurally characterized by a combination of IR, 1H NMR, mass spectrometry and single-crystal X-ray diffraction analyses.

The synthesis of 6-bromo-2,2-di-tert-butyl-4H-1,3,2-benzo[d]dioxagermine (1) via an alcohol/alkoxide exchange starting from di-tert-butyl-di-ethoxy germane is reported. Characterization of the title compound including single crystal X-ray diffraction and TGA/DSC analysis, mass spectrometry, 1H NMR, 13C{1H} NMR and IR spectroscopy is reported. DFT-D calculations have been carried out to assign the absorption band maxima of the IR spectrum to the corresponding vibrational modes. The suitability for Twin Polymerization of the novel dioxagermine 1 has been studied by TGA/DSC analysis and mass spectrometry. Proton-assisted Twin Polymerization of 1 results in an organic–inorganic hybrid material composed of a phenolic resin and [tBu2GeO]n.

The thermal and photochemical behavior of phenylethynyltris(trimethylsilyl)germane (1) has been reported. The thermolysis of 1 in the absence of a trapping agent in a sealed glass tube at 240 °C for 6 h gave 1,3-bis(trimethylsilyl)-1-tris(trimethylsilyl)germyl-1-germaindene (2) in 18% yield, together with phenyl(trimethylsilyl)acetylene in 60% yield. Similar thermolysis of 1 in the presence of 2,3-dimethylbutadiene afforded 3,4-dimethyl-1,1-bis(trimethylsilyl)-1-germacyclopent-3-ene (3) in 62% yield, along with phenyl(trimethylsilyl)acetylene. When 1 was irradiated with a low-pressure mercury lamp in the presence of a large excess of 2,3-dimethylbutadiene at room temperature for 10 min, compound 3 was obtained in 11% yield, in addition to 17% of phenyl(trimethylsilyl)acetylene and 31% of the starting compound 1. The photolysis of 1 in the absence of a trapping agent under the same conditions afforded phenyl(trimethylsilyl)acetylene as the sole volatile product. The DFT calculations were carried out to investigate the reaction mechanisms for the thermal reaction of 1 leading to the germaindene 2.

This paper describes the synthesis and comprehensive characterization of tetrakis(pentafluoroethyl)germane. In addition to a complete NMR spectroscopic characterization, including the rarely used 73Ge NMR spectroscopy, Ge(C2F5)4 was studied by IR spectroscopy, mass spectrometry as well as X-ray diffraction analysis. A 73Ge NMR investigation as well as an X-ray diffraction study of the related germane Ge(CF3)4 are also included.

The reaction of the silyl complex [Rh{Si(OEt)3}(PEt3)3] (1) with 3,3,3-trifluoropropene afforded the rhodium complex [Rh(CH2CHCF3){Si(OEt)3}(PEt3)2] (2) which features a bonded fluorinated olefin. In contrast the rhodium hydrido complex [Rh(H)(PEt3)3] (3) yielded on treatment with 3,3,3-trifluoropropene in the presence of a base the fluorido complex [Rh(F)(PEt3)3] (4) together with 1,1-difluoro-1-propene by C–F bond activation. At low temperature the intermediate fac-[Rh(H)(CH2CHCF3)(PEt3)3] (5) was detected by NMR spectroscopy. The germyl complex [Rh(GePh3)(PEt3)3] (6) reacted also with 3,3,3-trifluoropropene by C–F bond activation affording again the fluorido complex [Rh(F)(PEt3)3] (4) as well as the (3,3-difluoroallyl)triphenylgermane 7. The catalytic hydrogermylation of 3,3,3-trifluoropropene in the presence of various germanium hydrides under mild conditions was developed by employing complex 6 as a catalyst. The molecular structures of both germane derivatives (3,3-difluoroallyl)triphenylgermane 7 and 1,1,1-trifluoropropane-3-triphenylgermane 8 were determined by X-ray crystallography.

High quality Ge epitaxy on a GaAs (100) substrate was grown by metal-organic chemical vapor deposition using germane. The effects of growth temperature and deposition rate on the quality of the Ge epitaxy are investigated. Significant improvement in surface root-mean-square roughness is observed with increasing Ge growth temperature or deposition rate, while keeping all other deposition parameters unchanged. Investigation of the Ge material quality grown after different GaAs surface preparation conditions shows that Ga rich surfaces are beneficial for smooth Ge surfaces, which is attributed to the formation of Ge–Ga bonds at the initiation of the Ge deposition. The good crystalline quality of grown Ge film was further confirmed by high-resolution X-ray diffraction and secondary ion mass spectrometry characterization.

The activation of the Ge–H bond of Et 3 GeH and Et 2 GeH 2 in the photochemical reaction with W(CO) 6 and [W(CO) 4 (η 4 -nbd)] has been observed by 1 H NMR spectroscopy. The complex [{W(μ-η 2 -H–GeEt 2 )(CO) 4 } 2 ] has been isolated and characterized by NMR spectroscopy and by a single-crystal X-ray diffraction study. The activation of the Ge–H bond of triethylgermane has been applied in the hydrogermylation of norbornadiene. The geometry of several possible intermediate σ and hydride complexes formed in reaction of W(CO) 6 and Et 2 GeH 2 was estimated by DFT calculations.► The photochemical reaction of germanes with tungsten carbonyls has been studied. ► The activation of the Ge–H bond of germanes has been observed by 1 H NMR spectroscopy. ► The structure of complex [{W(μ-η 2 -H–GeEt 2 )(CO) 4 } 2 ] has been resolved by X-ray method. ► The geometry of complexes containing the W–Ge bond was estimated by DFT method. ► The 1 H NMR chemical shifts of the hydride ligands have been calculated.

A method has been developed for the extraction of single 71Ge atoms from the gallium target of a Ga-Ge neutrino detector. The key features of this chemical process stem from the extremely low content of the element to be extracted in the sample (n × 10−27 at %), the large sample weight (up to n × 103 kg), the limited time available for the extraction and measurement of the extracted atoms (≤20 h), and small permissible loss (≤0.1%) of the target material at high degrees of 71Ge extraction (≥90%). The method involves forced generation and maintenance of a disperse system of liquid gallium droplets with an oxide surface film in an acid-peroxide solution. The small droplet size ensures a rapid 71Ge transfer from the bulk target to a small amount of gallium oxide. The 71Ge passes from the oxide film to the solution, is concentrated, and converts to germane, which is delivered to a proportional counter. We have assessed the completeness of germanium extraction in relation to process conditions. The results, in particular the completeness of extraction, have been verified in experiments with Ga + Ge mixtures at germanium concentrations of 10−4 and 10−17 to 10−16 wt %. The adequacy of the approaches used to develop the technology of the Ga-Ge detector is supported by satisfactory agreement between the solar neutrino fluxes obtained with gallium and gallium-chloride detectors.

Treatment of diphenyl-di(phenylethynyl)germane with two equivalents of di( tert -butyl)aluminum hydride afforded the corresponding dialkenyl derivative, Ph 2 Ge[C(Al t Bu 2 ) C(H)–Ph] 2 ( 1 ) by dual hydroalumination. The aluminum atoms of 1 are attached to the carbon atoms in α-position to germanium. They are coordinatively unsaturated and are able to act as chelating Lewis-acids and to coordinate donors such as chloride or bromide anions in a chelating manner ( 2 , 3 ). The analogous reaction of the corresponding silicon-centered dialkyne with two equivalents of dimethylaluminum hydride gave a mixture of unknown compounds. Interestingly, equimolar quantities of the hydride and the dialkyne resulted in dismutation and the formation of the unprecedented compound MeAl[C( CH–Ph)–SiPh 2 –C C–Ph] 2 ( 4 ). Compound 4 has two alkenyl groups bonded to the central aluminum atom and a terminal alkynyl group attached to each silicon atom. An attempt to reduce the remaining triple bonds by reaction with di( tert -butyl)aluminum hydride resulted in cleavage and isolation of the monoalkenyl compound t Bu 2 Al–C[ C(H)–Ph]–SiPh 2 –C C–Ph ( 5 ). The molecular structure of 5 showed a close interaction between the α-carbon atom of the triple bond and the coordinatively unsaturated aluminum atom.

This Forum review describes the most recent achievements in the novel prospective field of highly reactive main-group organometallics, namely, geminal dianionic derivatives of the heavy group 14 elements (Si, Ge, Sn). A brief historical introduction to the topic is followed by discussion of the current state of affairs in the field of stable derivatives and prospects for future efforts, highlighting our own synthetic approach and recent results. The most important experimental contributions, including synthesis of 1,1-dilithiosilane, -germane, and -stannane derivatives; dilithio(halo)silanes (lithiosilylenoids); metallole 1,1-dianions; and heavy analogues of the cyclobutadiene dianion derivatives, are presented, along with a discussion of the synthetic applications of the above-mentioned organometallic compounds.

We report on the growth of n- and p-doped Germanium (Ge) on Ge substrates by Metal-Organic Vapor Phase Epitaxy (MOVPE). Iso-butyl germane, a liquid metal-organic source less toxic than Germane, is used as Ge precursor. We demonstrate the p-doping of Germanium by MOVPE using Trimethylgallium. The influence of the growth parameters for n and p-type doping is studied in order to optimize the morphology, the structural and the electrical properties of the Ge layers. The controlled growth of p and n doped Ge layers opens the possibility to realize totally epitaxially grown Ge diodes with improved performances, for example, for solar cell applications.

In the present work homoepitaxial Ge layers were deposited by means of metal organic vapor phase epitaxy (MOVPE) on Ge using iso-butyl germane (iBuGe) as a metal organic precursor. Layers of different thicknesses were grown by varying the deposition temperature between 550 and 700 °C on n- and p-type Ge substrates. The films were found to be intrinsically p-type with high carrier concentration, but using AsH3 it was possible to achieve n-type doping. TEM and X-ray diffraction were used to assess the good crystallographic quality of the layers. By depositing a p-type layer onto an n-type Ge substrate or, vice versa, an n-type layer on a p-type Ge substrate is was possible to realize p/n (or n/p) junctions. Mesa structures were realized in order to perform electrical characterizations of the junctions.

Plasma enhanced chemical vapor deposition (PECVD) of germanium selenide thin films from germanium tetrachloride and dimethyl selenide was studied to determine the viability of these reagents for thin film deposition. Germanium tetrachloride and alkylselenides were selected as candidates for these reactions due to their lower toxicities and higher availabilities compared to the more typical substitutes: germane and hydrogen selenide in the formation of germanium selenides. Dimethyl selenide was used successfully for the deposition of germanium selenides. Variation in film stoichiometry was observed by the modification of reactant gas flow ratios. Relative mass flow rates were varied in order to determine their effect on germanium chalcogenide deposition, and the effect of these flow rate modifications on the film thickness, structural properties, and composition are reported.

Reaction of nucleogenic dimethylgermylium cations with benzene in the gas phase was studied by the radiochemical method. The formation of the products of germylation of benzene, dimethylphenylgermane, and phenylgermane is indicative of the formation of dimethylgermylium cations by the β-decay of tritium in the molecule of dimethylditritium germane. Dimethylgermylium cations are shown to undergo a rearrangement in the course of the reaction with benzene, which is consistent with the earlier results of quantum-chemical calculations.

The synthetic and structural chemistry of catalytically useful trialkylsilylium salts with weakly coordinating carborane anions, R3Si(CHB11X11), has been extended to the heavier group 14 elements. Et3Ge(CHB11H5Br5) was prepared from Et3GeH and trityl CHB11H5Br6−. Its X-ray crystal structure shows ion-like character very similar to its Si congener. The heavier element analogues, Et3E(CHB11H5Br6) (E = Sn, Pb), were prepared by chloride ion abstraction from Et3SnCl and Et3PbCl, respectively, using Et3Si(CHB11H5Br6). Their crystal structures differ from those of the four-coordinate lighter elements by adopting five-coordinate trigonal-bipyramidal stereochemistries, reflecting the periodic table transition of these elements from semi-metals to metals. The carborane anions are weak, bridging, axial ligands connecting trigonal Et3E+ cation-like moieties in polymeric chain structures. When the less coordinating CHB11Cl11− anion is used, excess germane competes with the carborane anion for coordination to Ge and a...

In situ control over the growth morphology of nanocones has important implications to their application in photovoltaic and thermoelectric devices. In this study, Ge nanocones were grown by an Au-catalyzed process in a chemical vapor deposition (CVD) chamber using germane (GeH 4 ) as the source gas. The growth temperature was varied for different segments of the growth, and a corresponding variation of taper (angle of cone sidewalls relative to the axial direction) in the segments was observed. The structures obtained in these experiments reveal their temperature-dependent modes of growth. When the growth was conducted at an initial temperature of 350 °C then increased to 400 °C, faceted pillars consisting of a base segment of largely uniform diameter and a conical tapered tip were formed. When the growth was conducted at 395 and 375 °C, then at 350 °C, the nanocones featured a base with a wider taper and tips with a smaller taper. The dependence on temperature of the growth morphology is attributed to the relative influence of competing growth mechanisms at different temperature regimes: catalyzed unidirectional growth at lower temperatures approaching the Au–Ge eutectic point, and increasingly isotropic and facet-bounded epitaxial growth at higher temperatures up to 400 °C. The multi-step growth method also provides a reliable method of determining the rate and mode of catalyzed growth.

Tetrakis(trimethylgermyl)germane was prepared by the reaction of chlorotrimethylgermane and tetrabromogermane with lithium at −78 °C. Reaction with potassium tert-butoxide/18-crown-6 gave (Me3Ge)3G...

Treatment of the tetraethynylgermanium compound Ge(C≡CC6H5)4 4 with 2 equiv of H−Al[CH(SiMe3)2]2 yielded the addition product Ge(C≡CC6H5)2[C{AlR2}═C(H)C6H5]2 (5, R = CH(SiMe3)2) by reduction of two...

The cothermolysis of pivaloyl- and adamantoyltris(trimethylsilyl)germane (1 and 2) with methyl vinyl ketone and acrolein at 120 °C gave the respective six–membered ring compounds, 2-trimethylsiloxy-3,3-bis(trimethylsilyl)-3-germa-1-oxacyclohex-5-ene derivatives, arising from formal [2 + 4] cycloaddition of germenes with enones, along with appreciable amounts of the unchanged starting compounds. Similar thermolysis of 1 and 2 with methyl vinyl ketone and acrolein at 130 °C afforded two types of the products, [2 + 4] cycloadducts and acylbis(trimethylsilyl)germanes arising from the ring-opening reaction of the resulting cycloadducts, respectively. When 1 and 2 were heated in the presence of the same enones at 140 °C, acylbis(trimethylsilyl)germanes were obtained as the main products. The thermolysis of acylbis(trimethylsilyl)germane (3) with 2,3-dimethylbutadiene produced two stereoisomers of [2 + 4] cycloadducts. The results of theoretical calculations for the formation of germenes and [2 + 4] cycloaddition of the germenes to enones, and also isomerization of the resulting [2 + 4] cycloadducts, leading to the ring-opened products have also been reported.

We evaluate the hydrogen content in hydrogenated amorphous germanium- and carbon- and also boron- and phosphorus-doped nanocrystalline silicon films obtained by a plasma chemical deposition technique. The films were made of a silicon-containing mixture (silane) heavily diluted with hydrogen and an inert gas (argon), and also methane and germane. In the study we use a combination of Infrared spectroscopy, recoil proton method and X-rays diffraction analysis. The hydrogen content is found to be as great as16 at% for the nanocrystalline films and 24 at% for the alloys. The hydrogen content in the alloys increases with the carbon concentration and decreases with germanium.

A one-dimensional (1D) coordination polymer of stoichiometry [{{Ge(CH2SPh)4}HgBr2}n] (2b) has been prepared by treatment of HgBr2 with the functionalized germane Ge(CH2SPh)4 (1b), which is acting as a tetradentate thioether ligands. The extended structure results from weak intermolecular Hg–S interactions linking the monomeric {Ge(CH2SPh)4}HgBr2 units, as established using single-crystal X-ray diffraction. The effective coordination around the mercury atoms is best described as distorted octahedral. Upon reaction of CuI with 1b in a 2:1 metal-to-ligand ratio, the novel metal-organic polymer [{{Ge(CH2SPh)4}(Cu2I2)}n] (3), which incorporates rhombic dinuclear Cu(μ-I)2Cu units within its 2D sheet-like network, was obtained. The luminescence properties of 1b and 3 have been investigated both in solution and in the solid state. Upon treatment of 1b with [{Re(μ-Br)(CO)3(THF)}2] the mononuclear compound fac-[ReBr(CO)3{Ge(CH2SPh)4}] (4) is formed. In this chelate complex, two CH2SPh arms are ligated on ReI, the remaining two CH2SPh arms are dangling.

The germane intermediate σ-complexes, characterized by high-field resonances in the region from −6 to −8 ppm, have been detected during the 1 H NMR spectroscopy monitoring of the photochemical reaction of Et 3 GeH with Mo(CO) 6 , [Mo(CO) 4 (η 4 -cod)], and [Mo(CO) 4 (η 4 -nbd)] in the NMR tube. The activation of the Ge–H bond of germane in photochemical reaction of the norbornadiene (nbd) complex [Mo(CO) 4 (η 4 -nbd)] has been applied in the hydrogermylation of norbornadiene, which leads to the formation of triethylgermylnorbornene.

The laser flash photolysis of dodecamethylcyclohexagermane (1) and dimethylphenyl(trimethylsilyl)germane (5), two known photochemical precursors to dimethylgermylene (GeMe2), has been reinvestigated. Laser flash photolysis of 1 in hexane solution affords markedly different results than were reported in an earlier study of this compound in cyclohexane. The present study shows it to yield two primary transient products, one exhibiting λmax = 490 nm and lifetime τ ≤ 10 ns and a second that exhibits λmax = 470 nm and decays on the microsecond time scale with second-order kinetics, with the concomitant growth of absorptions centered at λmax = 370 nm due to tetramethyldigermene (Ge2Me4). The spectrum and absolute rate constants for quenching of the 470 nm species by acetic acid, 2,3-dimethyl-1,3-butadiene (DMB), CCl4, and oxygen in hexane, as well as the transient behavior observed in the presence of millimolar concentrations of THF, are all quite similar to those established recently for GeMe2 using 1-germacyc...

TEA CO2 laser-induced dielectric breakdown of an equimolar mixture of gaseous stannane and germane in Ar allows decomposition of both metal hydrides and chemical vapour deposition of the nanostructured Ge/Sn films. Analysis of the films by FTIR and Raman spectroscopy, X-ray diffraction analysis and electron microscopy revealed nanoregions of crystalline Sn and Sn-rich Ge/Sn alloys surrounded by an amorphous Ge/Sn phase. The crystalline Ge/Sn nanoalloys contain different amounts of Sn incorporated into the Ge lattice and undergo changes in composition at temperatures as low as 200 °C.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Epitaxial growth of germanium is attractive for Ge/III–V hetero devices such as multi-junction solar cells. We investigated the growth of Ge with iso-butyl germane (IBGe) as germanium source and found a strong memory effect in our AIX2600-G3 metalorganic vapor phase epitaxy (MOVPE) reactor. The germanium background led to a higher n-type doping of i-GaAs and strongly reduced the photoluminescence (PL) intensity of Al 0.3 Ga 0.7 As and Ga 0.5 In 0.5 P. With secondary ion mass spectroscopy (SIMS) the quantity of Ge in Al 0.3 Ga 0.7 As could be determined to be in the range of 2×10 17 cm −3 , whereas a Ge-atom concentration in Ga 0.5 In 0.5 P of up to 2×10 18 cm −3 was measured. The memory effect could be eliminated by changing all contaminated parts inside the MOVPE reactor.

Germane has been prepared through the electrochemical reduction of the germanate anion in alkaline solutions with a current efficiency of 40–45%. Active solution circulation in the cathodic zone and the use of an Sn or Cd cathode are shown to raise the germane yield. The current density and initial solution concentration have a weak effect on the reduction process.

Laser ablated chromium, molybdenum, and tungsten atoms react with germane during condensation in excess noble gases. The chromium reaction stopped at the germyl metal hydride, molybdenum gave some hydride but mostly germylidyne, and tungsten reacted spontaneously to give only the germylidyne species. These molecules were identified by isotopic shifts, density-functional theory product energy and frequency calculations, and comparison to the analogous methane and silane reaction products. Effective bond orders for the HGe≡MoH3 and HGe≡WH3 molecules are 2.82 and 2.87 using the B3LYP density functional, and are slightly lower than their silicon and carbon analogues. Our calculated Ge≡M triple bond lengths for these simple trihydride complexes are 0.05 to 0.10 A shorter than those measured for larger group 6 organometallic complexes.