Germanium Hydrides Research Articles

In situ concentration of metallic hydride in a graphite furnace coated with palladium—determination of bismuth, germanium and tellurium

An analytical method for the ultrasensitive determination of bismuth, germanium and tellurium is described. Analytes were reduced to their corresponding hydrides. A graphite tube coated with palladium was used as the collection medium and atomizer. Palladium was found to be a very efficient adsorber for bismuth, germanium and tellurium hydrides. The operating conditions were optimized, and the technique has been successfully applied to the determination of these elements in geological materials and natural water samples.

ChemInform Abstract: Thermolysis and Mass Spectra of Polymeric Germanium Hydride Produced by γ‐Radiolysis.

AbstractUpon heating solid polymeric Ge hydride, obtained by γ‐radiolysis of GeH4, undergoes two successive weight losses at 463 and 1173 K. At 948 K two crystal phases are formed, one of them being pure Ge.

Homolytic reactions of ligated boranes. Part 9. Overall addition of alkanes to electron-deficient alkenes by a radical chain mechanism

Methyl bromoacetate and ethyl 2-bromopropanoate are reduced by Bun3P→BH3 or Bun3P→BH2Ph to methyl acetate and ethyl proponoate, respectively, in chlorobenzene at 80–110 °C in the presence of dibenzoyl peroxide or t-butyl perbenzoate. Amine complexes of borane or phenylborane are much less effective reducing agents. The reductions may also be initiated photochemically and are inhibited by a phenolic radical scavenger. A homolytic chain mechanism is proposed in which the phosphine–boryl radical abstracts halogen from the bromo ester and is subsequently regenerated by reaction of an α-(alkoxycarbonyl) alkyl radical with the phosphine–borane. The latter propagation step, together with halogen abstraction from Rl and addition of the derived alkyl radical to the CC bond, is also involved in the chain reaction between Bun3P→BH2Ph, an alkyl iodide, and ethyl acrylate according to equation (A); Bun3P→BH3 reacts similarly but gives lower yields of ester. Reaction (A) proceeds smoothly at 110 °C Bun3P→BH2Ph + Rl + CH2CHCO2Et→RCH2CH2CO2Et + Bun3P→BHIPh (A) when initiated by t-butyl perbenzoate and moderate yields of isolated esters were obtained from n-butyl iodide, cyclohexyl iodide, and 3β-iodocholest-5-ene. This last iodide gives an epimeric mixture of 3α-and 3β-esters in total isolated yield of ca. 50%. Similar addition reactions take place between Bun3P→BH2Ph, Bunl, and diethyl vinylphosphonate or phenyl vinyl sulphone. It is concluded that Bun3P→BH3 and particularly Bun3P→BH2Ph offer promise as alternatives to tin, mercury, and germanium hydrides in radical chain reactions of synthetic value.

Thermolysis and mass spectra of polymeric germanium hydride produced by γ-radiolysis

TGA, MS and DSC of a solid polymeric Ge hydride, obtained by γ-radiolysis of GeH 4, are reported. Upon heating, it undergoes two successive weight losses at 463 and 1173 K. At 948 K two crystal phases are formed, one of them is pure germanium. Some comparisons with a-Ge: H produced via RF sputtering or glow discharge are reported.

Detectors for spectrometry of the X-ray emission from germanium obtained by the hydride method

This paper investigates certain characteristics of p-n structures, prepared on a base of germanium obtained by the hydride method. The purpose of the study is to estimate the degree of purity of the germanium and its applicability for the preparation of the detectors with a high energy resolution. Monocrysstals of the p type were used. On completion of diffusion of the lithium in the samples by means of the procedure described, a protective groove was cut out. The apparatus spectra of Fe-55 and Am-241 are shown. The characteristics of the detectors obtained confirm the excellent quality and high purity of the germanium hydride.

Alkyl additions to active olefins by tributylgermanium hydride reduction of alkyl halides

Tri( n -butyl)germanium hydride is a superior reagent for the reductive addition of alkyl halides to active olefins.

Determination of germanium in silicate rocks and sulphide ores by hydride generation and flame atomic-absorption spectrophotometry

A method is described for the generation of germanium hydride and the determination of germanium by atomic-absorption spectrophotometry. The hydride is generated continuously and is introduced directly into a dinitrogen oxide-acetylene flame. After digestion of the sample, the germanium is extracted directly into a mixture of carbon tetrachloride and 9 M hydrochloric acid. The final extraction is into distilled water, and the germanium hydride is generated with sodium tetrahydroborate(III). The method is free from interferences, and has been applied to the determination of germanium in silicate rocks and sulphide ores. The average recovery of the germanium that had been added to the sample before dissolution was 94%.

Interaction of pentafluorophenyl hydrides of germanium with triethylthallium

(C 6F 5) 3GeTlEt 2 and [(C 6F 5) 3Ge] 2TlEt have been prepared by reaction of tris(pentafluorophenyl)germane with triethylthallium. The reaction of the dihydride (C 6F 5) 2GeH 2 with triethylthallium gives an unusual product of composition [(C 6F 5) 2GeTlEt] n . The possible isomeric forms of this compound are discussed. Reactions of the compound obtained with (C 6F 5) 2GeH 2, bromine, hydrogen chloride and benzoyl peroxide have been studied. In the reaction with benzoyl peroxide the migration of an ethyl group from thallium to germanium has been noted.

Germaniumbestimmung durch Hydriderzeugung im Reduktionsrohr und nachfolgende Graphitofen-AAS mit CH4/Ar als Spülgas

A sensitive method for the hydride generation and graphite tube furnace atomic absorption spectrometric measurements with a reducing tube using mixed gas (CH4 10% + Ar 90%) as sweeper gas has been developed for the determination of germanium. Germanium hydrides were generated in a horizontal glass tube, in which a pellet of NaBH4 was placed. 0.61/min of sweeper gas flow rate, 2,700° C of atomization temperature and 2.5–3 M of acidity range were the best experimental conditions. The strong supression of the germanium signal by Ni and Co was effectively eliminated with 1,10-phenanthroline and thiosemicarbazide was comparatively effective for Au. The reducing tube used in this technique is extremely simple and can be connected to all the types of graphite furnaces. A detection limit of 2 ng was obtained with a precision of 3–4%

Features of the chain-transfer reaction of group IV B organo-metal compounds

The chain-transfer reaction of trisubstituted hydrides of silicon, germanium and tin (R 3MeH) have been studied in the polymerizations of vinyl monomers having different double bond polarities e. The rate constant of this reaction strongly depends on the type of the substituent R present in R 3MeH, the central atom Me, and the monomer polarity. Quantitative correlations have been established for the first time between the reactivity C p and the induction effect of the substituent ( Σσ s* —Taft constant) present in these metal hydrides; this is regarded as experimental proof of the hypothesis that polarity has a decisive effect in the intermediate stage of the chain-transfer reaction. The R 3MeH addition does not affect the stationary rate and reduces gelling during high-conversion polymerization. The possibility is shown of a block copolymer synthesis by a radical polymerization over poly-functional group IV B metal compounds.

Determination of germanium in coal ashes by hydride generation and flame atomic-absorption spectrophotometry

This paper describes the determination of germanium by atomic-absorption spectrophotometry with direct introduction into a dinitrogen oxide-acetylene flame of the germanium(IV) hydride generated by reducing with sodium tetrahydroborate(III) solution. A comparative study of the sensitivity of the germanium determination has been carried out and a study of interferences from lead(II), arsenic(III) and -(V), iron(II) and -(III), tellurium(IV), selenium(IV), antimony(III), tin(II), tartrates, oxalates and fluorides is described. The sensitivity of the proposed method is 0.012 µg ml–1 and the detection limit is approximately 100 times better than obtained with silica tube atomisation at a wavelength of 265.14 nm. The method has been applied to the determination of germanium in lignite ashes with an average germanium recovery of 97.65% and a relative standard deviation of 2.87%.

Hexamethylsilirane; ring cleavage by germanium and tin hydrides

Under the appropriate conditions, organogermanium and organotin hydrides react with hexamethylsilirane to give ring-opening products of type R 3GeSiMe 2(CMe 2CMe 2H and R 3SnSiMe 2(CMe 2CMe 2H), respectively (CMe 2CMe 2H) and R 3SnSiMe 2(CMe 2CMe 2H), respectively.

Effect of silicon, germanium and tin compounds on copolymerization of unsaturated acids

A study was made of the effect of silicon, germanium and tin compounds on copolymerization of methacrylic and acrylic acids with vinyl monomers. It was established that chlorides and trisubstituted hydrides of silicon, germanium and tin result in a reduction of the content of acid units in the copolymer, the effect markedly depending on the type of substituent and the main element of the modifier of the system. A distinctive feature of new modifiers is the action on copolymerization in catalytic amounts not exceeding 1% in the monomer mixture. It was shown that charge transfer complexes are formed between unsaturated acids and compounds of elements of group IVB. An assumption was put forward that the variation in copolymer composition is the consequence of interaction of the modifier with the intermediate complex, as a result of which the level of resonance stabilization is lowered.

Base-catalysed hydrogen-exchange between organogermanium hydrides and methanol

First order rate constants have been determined for the loss of tritium from tritiated germanium hydrides in MeOH/MeONa at 20–40°C. The rate constant for Ph 3GeT (T = 3H) is greater than that for exchange at the 9-position of fluorene under similar conditions. Values of k rel, the rate relative to that for Ph 3-GeH, for (XC 6H 4) 3GeT compounds at 30°C are: (X =) m-Cl, 380; p-Cl, 71; m-Me, 0.48; p-Me, 0.078; o-Me, 0.081; p-OMe, 0.025; o-Me, 0.018, and there is a good linear correlation between log k rel and σ. For the compounds (XC 6H 4)-Ph 2GeT the values of k rel are (X =) p-NO 2, 1280; p-CN, 680; m-Cl, 10; and p-F, 1.1, and a plot of log k rel against σ − constants is much better than that against σ constants. The results imply that there is substantial delocalization of charge from the anionic germanium centre into the aromatic rings, and thus na important degree of ( p p) π bonding between the germanium atom and these rings in the anion. The rates of exchange fall on going from Ph 3GeT to Ph 2GeHT, to PhGeH 2T (the values of k rel being 1, 0.11, and ca. 0.015 respectively), implying an order of kinetic acidities opposite to the reported order of equilibrium acidities in liquid ammonia. Replacement of Ph by Et groups also leads to a fall in kinetic acidity, values of k rel for EtPh 2GeT and Et 3GeT being 6 × 10 −2 and ca. 3 × 10 −3, respectively. Solvolysis, involving generation of hydrogen, is significant for PhGeH 3 under the reaction conditions, and important for Et 3GeH. The value of the inverse solvent isotope effect, k MeOD/ k MeOH is ca. 1.7 for both Ph 3GeT and ( m-ClC 6H 4) 3 GeT at 20°C. This value, and the activation parameters determined for some of the (XC 6H 4) 3GeT compounds are consistent with a transition state for the rate-determining step in which the hydrogen is roughly half transferred from germanium to methoxide ion, with partial liberation of the methanol molecules initially solvating the latter.

Study of decomposition of germanium hydride when it proceeds as deflagration combustion

1. The values of the quenching distance, the minimum ignition energy, the normal combustion rate, the limiting pressure, and the flame temperature were determined for the decomposition of GeH4. 2. On the basis of the obtained data the Peclet criterion was calculated to be equal to 6, which is substantially lower than its average value for the combustion processes of gases. The theory was advanced that the divergence is explained by the effect of the heterogeneous reaction for the thermal decomposition of GeH4 on the mechanism of spreading the flame in narrow channels.

Organogermanium compounds : II. Reduction of organic halides with hydrogermanes

The scope of the reduction of organic halides with trialkylgermanes under homolytic condition has been studied. Germanium hydrides can reduce polyhaloalkane without catalysts under mild conditions, the homolytic mechanism being, however, established for the uncatalyzed reduction. The observed orders of reactivity and selectivity in the reduction are consistent with a radical chain mechanism involving free germyl radicals. Some synthetic applications are described.

Volatile compounds of the hydrides of silicon and germanium with elements of Groups V and VI

Volatile compounds of the hydrides of silicon and germanium with elements of Groups V and VI

TheK-shell fluorescence yield of germanium

TheK-shell fluorescence yield of germanium has been determined asωK=0.570±0.003 by the modified proportional counter technique using a special wall-less proportional counter filled with methane and small admixture of germanium hydride GeH4. The required ratio of the total photoabsorption to the absorption in theK-shell has been obtained from the separate study of the energy dependence of the X-ray absorption in germanium.

Polar mechanisms in germanium and tin hydride reductions

Polar mechanisms in germanium and tin hydride reductions

Synthesis of the hydrides of germanium, phosphorus, arsenic, and antimony by the solid-phase reaction of the corresponding oxide with lithium aluminum hydride

Synthesis of the hydrides of germanium, phosphorus, arsenic, and antimony by the solid-phase reaction of the corresponding oxide with lithium aluminum hydride