3265-03-0Relevant articles and documents
Synthesis of silylium and germylium ions by a substituent exchange reaction
Schaefer, Andre,Reissmann, Matti,Jung, Sebastian,Schaefer, Annemarie,Saak, Wolfgang,Brendler, Erica,Mueller, Thomas
, p. 4713 - 4722 (2013/09/24)
The reaction of diarylalkylsilanes and -germanes with trityl cation in the presence of a weakly coordinating anion to give the corresponding triarylsilylium or -germylium ions was investigated. This reaction provides a facile access to a larger range of these sterically highly hindered Lewis acids. The factors that promote the substituent exchange were studied, and significant effects of the substituent, of the solvent, and of the group 14 element were revealed. A combined solid-state XRD and NMR investigation of the tris(pentamethylphenyl) silylium borate [(Me5C6) 3Si]2[B12Cl12] disclosed the trigonal planar coordination environment of the silicon atom in this silylium ion. NMR investigations indicate for 2,4,6-triisopropylphenyl-substituted silylium and germylium ions the onset of C-H···E + three-center interactions (E = Si, Ge) between the distant CH bond of the isopropyl group and the positively charged group 14 element atom.
Etude du transfert monoelectronique entre des germylanions et des piegeurs de spin dia et paramagnetiques
Riviere, P.,Castel, A.,Desor, D.,Abdennadher, C.
, p. 51 - 60 (2007/10/02)
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.
Nouveaux aryldihydrogermyllithium
Castel, A.,Riviere, P.,Satge, J.,Desor, D.
, p. 49 - 61 (2007/10/02)
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.
TRIMESITYLGERMYLAMINE Mes3GeNH2: SYNTHESES, STRUCTURE, PROPRIETES
Riviere-Baudet, Monique,Morere, Alain,Onyszchuk, Mario,Satge, Jacques
, p. 75 - 90 (2007/10/02)
Sterically hindered trimesitylgermylamine is a rare example of a stable primary germylamine.X-ray structural data show that germanium is shielded from nucleophilic attack by the surrounding mesityl groups.Nitrogen is still accessible, and the only reactions which occur are those in which the first step of the transition state proceeds through an electrophilic attack on nitrogen.With acid chlorides, Mes3GeNH2 reacts mainly as a primary amine forming the corresponding N-germylamides.The primary amine behaviour is also evident in the reaction with aldehydes.However, functional hydrogen cannot be substituted by lithium, probably because of steric hindrance which prevents the approach of an organolithium derivative.Insertion reactions into the Ge-N bond are difficult.Carbon dioxide and disulfide react only upon heating and yield trimesitylgermyliso- or isothiocyanates (Mes3GeN=C=X; X = O, S) through thermal degradation of the carbamate or dithiocarbamate initially formed. 3,5-di-tert-butylorthoquinone does not form an adduct with Mes3GeNH2, but is slowly transformed into 3,5-di-tert-butylorthocatechol.In spite of its steric hindrance, the trimesitylgermylamino group failed to stabilize a N-germylated germa-imine since the precursor Mes3Ge(Cl)NH-GeMes3 is not stable and gave cyclodigermazane (Mes2GeNH)2 and trimesitylgermyl chloride through Ge-Cl/Ge-N exchange reactions. Key words: Trimesitylgermylamine; 4-methyl 1-trimesitylgermoxy-benzene; N-trimesitylgermyl 2,2-dimethylpropanamide; trimesitylgermylisocyanate; trimesitylgermylisothiocyanate; tetramesitylcyclodigermazane.
Trimesitylgermyllithium: synthese et reactivite
Castel, A.,Riviere, P.,Satge, J.,Ko, Y.H.,Desor, D.
, p. 7 - 15 (2007/10/02)
The new organogermyllithium Mes3GeLi has been prepared in good yield by hydrogermolysis reaction of t-butyllithium in THF.The bulky group favours stabilization in the form of the THF complex.Mes3GeLi has been characterized by alkylation reaction with MeI.
TRIARYL-SILYL, -GERMYL, AND -STANNYL RADICALS MAr3 (M=Si, Ge, OR Sn AND Ar=2,4,6-Me3C6H2) AND Ge(2,6-Me2C6H3)3: SYNTHESIS AND ESR STUDIES
Gynane, Michael J. S.,Lappert, Michael F.,Riley, Paul I.,Riviere, Pierre,Riviere-Baudet, Monique
, p. 5 - 12 (2007/10/02)
The triarylmetal-centred radicals MAr3 (M=Si, Ge, or Sn: Ar=2,6-Me2C6H3 or 2,4,6-Me3C6H2) have been prepared from the appropriate triarylmetal chloride, MAr3Cl, and an electron-rich olefin >2 (R=Me or Et) under UV irradiation in toluene at low
