- A RE-EXAMINATION OF THE ELECTROCHEMICAL REDUCTION OF HALOSILANES AND HALOGERMANES
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The electrochemical reduction peaks previously observed at about -0.4 V vs.SCE in the case of chloro- or bromo-silanes and -germanes actually refer to reduction of HCl or HBr formed by hydrolysis arising from traces of water in the solvent.This hydrolysis is catalysed by nucleophilic solvents.The electrochemical reduction of halo-silanes and -germanes in aprotic solvents giving the corresponding disilanes and digermanes is shown to be an irreversible process taking place at a low potential (-2 to -2.5 V vs.SCE).
- Corriu, R. J. P.,Dabosi, G.,Martineau, M.
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- Photodecompostion of the Oligogermanes nBu3GeGePh2GenBu3 and nBu3GeGePh3: Identification of the Photoproducts by Spectroscopic and Spectrometric Methods
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The oligogermane nBu3GeGePh2GenBu3was photolyzed using UV-C light in the presence of acetic acid as a trapping agent and the photoproducts were identified using1H NMR spectroscopy, gas chromatography/electron-impact mass spectrometry, and high resolution accurate mass mass spectrometry. The products identified were the germanes nBu3GeH, nBu3GeOAc, and Ph2Ge(H)OAc (OAc = C2H3O2) and the digermane nBu6Ge2. This indicates that both germanium–germanium single bonds are cleaved homolytically upon irradiation to generate two nBu3Ge·radicals and the germylene Ph2Ge:. The digermane nBu3GeGePh3was also photolyzed under identical conditions, and in this case the photoproducts were identified as nBu3GeH, nBu3GeOAc, Ph3GeH, Ph3GeOAc and the digermanes nBu6Ge2and Ph6Ge2.
- Komanduri, Sangeetha P.,Schrick, Aaron C.,Feasley, Christa L.,Dufresne, Craig P.,Weinert, Charles S.
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p. 3196 - 3203
(2016/07/14)
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- Chemistry of homoleptic phenylethynyl complexes of lanthanides
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Methods to prepare homoleptic phenylethynyl complexes of lanthanides, the products properties and possible applications in organoelement synthesis of polyfunctional compounds are discussed.
- Zhiltsov,Druzhkova,Pimanova,Makarov
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p. 1910 - 1919
(2015/10/12)
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- Reaction of germanes and digermanes with triflic acid: The route to novel organooligogermanes
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Novel germanium containing triflates were prepared from the reactions of trifluoromethanesulfonic acid with tetraphenylgermane (1) and digermanes (Ph3GeGeMe3 (4), Ph3GeGePh3 (5)). The improved procedures for synthesis of known organogermanium compounds (Ph4Ge (1), Ph3GeCl (2), Ph3GeGeMe3 (4), Ph3GeGePh3 (5)) were also presented. The crystal structure of Ph3GeOTf (6) and Ph2Ge(OTf)Ge(OTf)Ph 2 (7) was studied by X-ray analysis. In 7 each germanium atom is pentacoordinated due to intramolecular interaction with O atom of the neighboring triflate group.
- Zaitsev, Kirill V.,Kapranov, Andrey A.,Oprunenko, Yuri F.,Churakov, Andrei V.,Howard, Judith A.K.,Tarasevich, Boris N.,Karlov, Sergey S.,Zaitseva, Galina S.
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p. 207 - 213
(2012/03/26)
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- Hydrogermolysis reactions involving the α-germylated nitriles R3GeCH2CN (R = Ph, Pri, But) and germanium amides R3GeNMe2 (R = Pri, But) with Ph3GeH: Substituent-dependent reactivity and crystal structures of Pri3GeGePh3 and But3Ge[NHC...
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Title full: Hydrogermolysis reactions involving the α-germylated nitriles R3GeCH2CN (R = Ph, Pri, But) and germanium amides R3GeNMe2 (R = Pri, But) with Ph3GeH: Substituent-dependent reactivity and crystal structures of Pri3GeGePh3 and But3Ge[NHC(CH3)CHCN]. The α-germylated nitriles R3GeCH2CN (R = Ph, Pri, But) and germanium amides R3GeNMe2 (R = Pri and But) have been prepared and characterized and their reactivity with Ph3GeH in CH3CN has been explored to investigate their utility for the construction of Ge-Ge bonds. In each case the phenyl and iso-propyl derivatives furnish the corresponding digermanes R3GeGePh3 (R = Ph, Pri) where the amide reagents are converted to R3GeCH2CN in situ which subsequently react with Ph3GeH. The rate of the Ge-C bond cleavage reactions was found to depend on the steric and electronic properties of the organic substituents. Attempted synthesis of But3GeGePh3 by these methods did not result in the desired product but rather in isolation of the 3-amidocrotononitrile species But3Ge[NHC(CH3)CHCN]. The crystal structures of Pri3GeGePh3 and But3Ge[NHC(CH3)CHCN] have been determined.
- Amadoruge, Monika L.,DiPasquale, Antonio G.,Rheingold, Arnold L.,Weinert, Charles S.
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p. 1771 - 1778
(2008/09/18)
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- Reactivity of 2,6-diethyl-4,8-dimethyl-1,5-dioxo-s-hydrindacene towards radical, anionic and cationic germylation
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The synthesis and diastereoisomeric resolution of 2,6-diethyl-4,8-dimethyl- 1,5-dioxo-s-hydrindacene allowed the determination of the structure of the meso compound by X-ray diffractometry. The diastereoisomers were inactive towards radical germylation but reacted with acidic hydrogermanes or germylithium yielding α-germylated alcohols. By contrast, they were poorly reactive towards germylamines or SET reactions. This diketone acts as an efficient spin trap in radical hydrogermylation of alkenes.
- El Kadib,Castel,Delpech,Rivière,Rivière-Baudet,Gornitzka,Aguirre,Manriquez,Chavez,Abril
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p. 1256 - 1264
(2008/10/09)
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- Reactivity of triphenylmethyl and triphenylgermyl derivatives of lanthanides
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Reactions of bis(triphenylmethyl)ytterbium and bis(triphenylgermyl) ytterbium with mercuric chloride, triphenylbismuth, iodine, tert-butyl alcohol, phenylacetylene, and cyclopentadiene were studied. The higher reactivity of the former compound in these re
- Zhil'tsov,Makarov,Semkina
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p. 1395 - 1397
(2007/10/03)
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- Study of reactions of some halides, cyclopentadienyl dichlorides, and bis(cyclopentadienyl) chlorides of lanthanides with trans-stilbene adducts with alkali metals [PhCHCHPh].-M+ (M = Li, Na)
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Reaction of Sml2(THF)2 with metallic lithium and trans-stilbene in 1 : 2 : 2 ratio in DME gives the stilbene complex of divalent samarium (PhCHCHPh)Sm(DME)2. This complex reacts with hydrogen in THF to give SmH2(THF)2 and 1,2-diphenylethane. The reaction with (Me3Si)2NH gives the amide [(Me3Si)2N]2Sm(DME)2 and the reaction with triphenylgermane yields Ph3GeGePh3. Reaction of CpLuCl2(THF)2 with 2 equivalents of [PhCHCHPh].- Na+ in DME results in the dimerization of stilbene fragments to give an ate-complex {Cp2Lu[μ-CH(Ph)CH(Ph)CH(Ph)CH(Ph)]}Na(DME)3. In the reaction of Cp2GdCl with [PhCHCHPh].- Na+, the known complex Cp3Gd(THF) was isolated as the only lanthanide-containing product.
- Trifonov,Fedorova,Kirillov,Bochkarev,Girgsdies,Schumann
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p. 1436 - 1439
(2007/10/03)
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- A novel route to triphenylgermyl europium complexes. Crystal structure of(Ph3Ge)2Eu(DME)3
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(Ph3Ge)2Eu(THF)4 (1a) and (Ph3Ge)2Eu(DME)3 (1b) have been synthesized by reacting Ph3GeH with europium naphthalene, C10H8Eu(THF)2, in THF or DME, respectively. The reaction of Ph3GeH with C10H8[EuI(DME)2]2 in DME yielded Ph3GeEuI(DME)2 (2). The addition of two equivalents of CH3I to a solution of 1b in THF produced Ph3GeMe and EuI2(DME)2 with almost quantitative yields. Complex 2 easily disproportionates forming mixtures of 1b and EuI2(DME)2. The molecular structure of 1b was determined from X-ray diffraction data.
- Fedorova, Elena E.,Trifonov, Alexander A.,Bochkarev, Mikhail N.,Girgsdies, Frank,Schumann, Herbert
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p. 1818 - 1822
(2008/10/08)
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- Etude du transfert monoelectronique entre des germylanions et des piegeurs de spin dia et paramagnetiques
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Reactions between organogermyllithium R3GeLi and several substrates favoring SET reactions (3,5-di-t-butyl-orthoquinone, fluorenone, tetracyanoquinodimethane, 2,4,6-tri-t-butylnitrosobenzene, etc.) lead mainly to the formation of digermanes and O- or N-germyl adducts.All these reactions seem to proceed principally by single-electron transfer.An ESR study of the reaction shows transient organic radical anion formation and germanium-centred radicals R3Ge.The prepondancy of this mechanism can be demonstrated by the reaction between R3GeLi and a paramagnetic quinonic species, the galvinoxyl radical: the latter is almost completely transformed into a diamagnetic anion.Digermanes mainly produced in these reactions are formed via radicalar duplication as well as lithiogermolysis of reaction adducts.
- Riviere, P.,Castel, A.,Desor, D.,Abdennadher, C.
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- Nouveaux aryldihydrogermyllithium
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The new aryldihydrogermyllithium complexes RH2GeLi (R = Ph, Mes) are prepared, in good yields, by metallation of the parent trihydrogermane with t-butyllithium in THF.They are characterized by alkylation reactions with MeI.Some germylation reactions are reported: they lead to the formation of new functional aryldihydrogermanes and aryldigermanes by a nucleophilic substitution.These aryldihydrogermyllithium complexes react also with acyl chlorides RCOCl (R = Ph, Mes) to give new diacyl- and triacyl-germanes.These easily add to the carbonyl group of aromatic aldehydes, thereby giving the corresponding α-germyl alcohols.
- Castel, A.,Riviere, P.,Satge, J.,Desor, D.
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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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- Etude de la reaction de germyllithiums sur la di-t-butyl-3,5 orthoquinone: mise en evidence d'un mecanisme par transfert monoelectronique
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Reactions between organogermyllithiums R3GeLi and 3,5-di-t-butylorthoquinone mainly give digermanes but also O-germylcatechol and germadioxolanes.It appears that these reactions start after an initial single electron transfer (SET) which is supported by a
- Riviere, P.,Castel, A.,Ko, Y. H.,Desor, D.
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p. 147 - 156
(2007/10/02)
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- Photochemical Regioselective Addition of Alkylacylgermanes to Styrene
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Photochemical addition of alkylacylgermanes to styrene has been achieved to give regioselective 1 : 1 and 2 : 1 adducts of acylgermanes to styrene in good yields.
- Kiyooka, Syun-ichi,Hamada, Maki,Matsue, Hideaki,Fujiyama, Ryoji
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p. 1385 - 1386
(2007/10/02)
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- UEBER POLYGERMANE XIV. POLYGERMANE ALS NEBENPRODUKTE DER GRIGNARD-REAKTION VON PhMgBr MIT GeCl4
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The synthesis of GePh4 and Ge2Ph6 by Grignard reaction in THF or ether/toluene leads to the by-products Ge3Ph8 (up to 11 percent) and Ge4Ph10 (up to 18 percent) which is dependant on using an excess of Mg.A quantitative analysis of the resulting products by HPLC and a semipreparative separation by column, flash, and HPL chromatography is described.The crystal structures of Ge3Ph8 (R=0.075) and Ge4Ph10*2C6H6 (R=0.054) have been determined.Ge4Ph10 has Ci symmetry and both chain conformations are well staggered (49-70 deg for Ge3Ph8, 53-66 deg for Ge4Ph10).The Ge-Ge distances and Ge-Ge-Ge angles are 244 pm and 121 deg (Ge3Ph8), and 246 pm and 118 deg (Ge4Ph10).
- Roller, Stefan,Simon, Dietolf,Draeger, Martin
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- POLYGERMANES PRECURSEURS D'ESPECES DU GERMANIUM A COORDINNANCE NON USUELLE
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Several thermal or photochemical α-elimination reactions of functional polygermanes lead to germylenes, R2Ge.Photolysis of polygermanes, cyclopolygermanes and polygermylmercury compounds and also hydrogen abstraction from various organohydropolygermanes using t-BuO., lead to the formation of polymetallated chains containing one or two germanium-centered radicals.These polygermyl radicals give germylenes, R2Ge, germanium centered radicals Ge., α-digermyl diradicals (or digermenes) Ge.-Ge. or Ge=Ge> and β- or γ-polygermyl diradicals via ahomolytic monoelectronic α-elimination process.In some cases the formation of α-digermyl diradicals or digermenes can also be seen as occuring through dimerization of germylenes but with lower yields.All these intermediates have been characterized by several trapping reactions with dimethyl disulfide, 2,3-dimethylbutadiene or biacetyl.
- Riviere, P.,Castel, A.,Satge, J.,Guyot, D.
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p. 193 - 206
(2007/10/02)
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- METHYLPHENYLTRIPHENYLGERMYLSILANES FONCTIONNELS OPTIQUEMENT ACTIFS
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The structure of the unsymmetric compound MePh(X)SiGePh3 (X=H, F, Cl, OR) has been resolved.The stereochemistry of nucleophilic substitutions at silicon is not changed with Ph3Ge as substituent.Stereochemical correlations allow the determination of absolute configurations.
- Corriu, R. J. P.,Ould-Kada, S.,Lanneau, G.
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- ELECTROCHEMICAL REDUCTION OF TRIORGANOHALO-SILANES AND -GERMANES
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The electrochemical reduction of triorganohalo-silanes and -germanes in 1,2-dimethoxyethane has been investigated by polarography, cyclic voltammetry, controlled potential coulometry, and macroscale electrolysis.The reduction of the silicon compounds exhibits a single irreversible wave.The polarograms for the germanium compounds exhibit two irreversible waves.The second wave shifts to more anodic potentials with addition of phenol or acetic acid.Dimer (i.e. disilanes or digermanes) are the main product of macroscale electrolysis in aprotic solvent but the hydrides are the principal products in protic solution.The results are interpreted in terms of the coexistence of two separate processes.The first involves a one electron reduction followed by dimerization of the radical.At higher cathodic potential a two electron charge transfer step occurs to form an anion, which in aprotic solvents reacts with the starting halogeno compound to form dimer, and in protic solutions gives the hydride.
- Corriu, R. J. P.,Dabosi, G.,Martineau, M.
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