- XAS/EXAFS studies of Ge nanoparticles produced by reaction between Mg 2Ge and GeCl4
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We present results of an XAS and EXAFS study of the synthesis of Ge nanoparticles formed by a metathesis reaction between Mg2Ge and GeCl4 in diglyme (diethylene glycol dimethyl ether). The progress of the formation reaction and the products formed at various stages in the processing was characterised by TEM and optical spectroscopy as well as in situ XAS/EXAFS studies using specially designed reaction cells.
- Pugsley, Andrew J.,Bull, Craig L.,Sella, Andrea,Sankar, Gopinathan,McMillan, Paul F.
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- Preparation of germatranyl triflates: Reactions of germatranes N(CH2CHRO)3X (X=Br, OTf, OSiMe3; R=H, Me) with lithium reagents
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New germatranes N(CH2CHRO)3GeOTf (4a, R=H; 4b, R=Me) were prepared in quantitative yield by treatment of N(CH2CHRO)3GeOSiMe3 (2a and 2b), with Me3SiOTf. The reactions of germatranes N(CH2CHRO)3GeX [3a, X=Br, R=H; 4a, X=OSO2CF3, R=H; 4b, X=OSO2CF3, R=Me; 2a, X=OSiMe3, R=H; 2b, X=OSiMe3, R=Me] with LiY reagents were studied. A series of germatranes N(CH2CHRO)3GeY [5a, R=H, Y=Ind (indenyl); 5b, R=Me, Y=Ind; 6a, R=H, Y=N(SiMe3)2; 6b, R=Me, Y=N(SiMe3)2; 7a, R=H, Y=Cp (cyclopentadienyl); 7b, R=Me, Y=Cp; 8a, R=H, Y=Flu (fluorenyl); 9a, R=H, Y=t-Bu] were obtained by nucleophilic substitution with the corresponding LiY reagent. Reactions of N(CH2CHMeO)3GeOSiMe3 (2b) and N(CH2CH2O)3GeBr (3a) with excess n-BuLi and of N(CH2CH2O)3GeOSiMe3 (2a) with excess LiNMe2 led to the formation of n-Bu4Ge and (Me2N)4Ge. The structures of new germatranes 4a, 4b, 6b and 7b were confirmed by NMR spectroscopy, mass spectrometry and elemental analyses.
- Karlov, Sergey S.,Shutov, Pavel L.,Akhmedov, Novruz G.,Seip, Markus A.,Lorberth, J?rg,Zaitseva, Galina S.
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- IR Spectra of n-Bu4M (M = Si, Ge, Sn, Pb), n-BuAuPPh3-d15, and "n-Bu" on a Gold Surface
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Observed and DFT-calculated IR spectra of n-Bu4M (M = Si, Ge, Sn, Pb), (CH3CH2CH213CD2)4Sn, and n-BuAuPPh3-d15 are reported and assigned. The asymmetric CH stretching vibration of the CH2 group adjacent to the metal atom appears as a distinct shoulder at ～2934 cm-1, whereas for other CH2 groups it is located at ～2922 cm-1. The characteristic peak at ～2899 cm-1 is attributed to an overtone of a symmetric CH2 bend at ～1445 cm-1. In n-BuAuPPh3-d15, the CH stretching vibrations of the butyl group are shifted to lower frequencies by ～10 cm-1, and two possible rationalizations are offered.
- Kaleta, Ji?í,Bednárová, Lucie,?í?ková, Martina,Wen, Jin,Kaletová, Eva,Michl, Josef
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- Cp2TiCl2 catalyzed one-pot synthesis of n-Bu3GeH from GeCl4
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The reaction of GeCl4 with n-BuMgCl in presence of a catalytic amount of Cp2TiCl2 gives n-Bu3GeH and n-Bu4Ge in ca. 70 and 25% yield, respectively. This method provides an industrially feasible one-pot synthesis for Bu3GeH and Bu4Ge. The reaction temperature and stoichiometry seem to be important in the distribution of the products. Apart from elemental analysis these compounds have been characterized by comparing their boiling points, NMR spectral data and GC assay with that of the authentic samples.
- Colacot, Thomas J.
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- Tributylgermanium hydride as a replacement for tributyltin hydride in radical reactions
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Tributylgermanium hydride (Bu3GeH) can be used as an alternative to tributyltin hydride (Bu3SnH) as a radical generating reagent with a wide range of radical substrates. Tributylgermanium hydride has several practical advantages over tributyltin hydride, e.g. low toxicity, good stability and much easier work-up of reactions. The reagent can be easily prepared in good yield and stored indefinitely. Suitable substrates include iodides, bromides, activated chlorides, phenyl selenides, tert-nitroalkanes, thiocarbonylimidazolides and Barton esters. Alkyl, vinyl and aryl radicals can be generated in radical reactions including reduction and cyclisation processes. Common radical initiators such as ACCN and triethylborane can be used. The slower rate of hydrogen abstraction by carbon-centred radicals from Bu 3GeH as compared to Bu3SnH facilitates improved cyclisation yields. Polarity reversal catalysis (PRC) with phenylthiol can be used in reactions which generate stable radical intermediates which will not abstract hydrogen from Bu3GeH.
- Bowman, W. Russell,Krintel, Sussie L.,Schilling, Mark B.
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p. 585 - 592
(2007/10/03)
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- Reactivity of dianionic hexacoordinate germanium complexes toward organometallic reagents. A new route to organogermanes
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Lithium and potassium tris(benzene-1,2-diolato)germanates (2a and 2b, respectively) and potassium tris(butane-2,3-diolato)germanate (3) are easily prepared from GeO2 in quantitative yields. They are very reactive toward organometallic reagents, the reactivity depending on the ligands on the germanium. Complexes 2 react with an excess of Grignard reagent to give the corresponding tetraorganogermanes R4Ge while the less reactive complex 3 leads to the functional triorganogermanes R3GeX. Tetraorganogermanes can also be prepared from complex 2b by reaction with organic bromides in the presence of Mg (Barbier reaction). The influence of Cp2TiCl2 and MgBr2 on the reactivity of Grignard reagents with these complexes was also investigated: in both cases formation of triorganogermanes was favored.
- Cerveau,Chuit,Corriu,Reyé
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p. 1510 - 1515
(2008/10/08)
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- Reactions of nucleophilic reagents with dianionic hexacoordinated germanium complexes: A new convenient route to functional organogermanes from germanium dioxide
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Tetraorganogermanes and triorganogermanes can be prepared in two steps from GeO2: the preparation of the anionic hexacoordinated germanium complexes followed by reaction of these with Grignard reagents to give the organogermanes.
- Cerveau,Chuit,Corriu,Reye
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p. 786 - 787
(2008/10/08)
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