1068-69-5Relevant articles and documents
Crystal structures of organometallic compounds of lithium and magnesium containing the bulky ligands C(SiMe3)2(SiMe2X) X=Me, Ph, NMe2, or C5H4N-2
Al-Juaid, Salih S.,Avent, Anthony G.,Eaborn, Colin,El-Hamruni, Salima M.,Hawkes, Simon A.,Hill, Michael S.,Hopman, Martijn,Hitchcock, Peter B.,Smith, J. David
, p. 76 - 86 (2007/10/03)
The complex [Li(TMEDA){C(SiMe3)2SiMe2NMe2}] (1) (TMEDA=N,N,N′,N′-tetramethylethane-1,2,-diamine) was found to crystallise with an internally coordinated structure like that of [Li(THF)2{C(SiMe3)2SiMe2NMe 2}] (THF=tetrahydrfuran). In contrast, the compound with Ph in place of NMe2 crystallised as a dialkyllithate [Li(TMEDA)2][Li{C(SiMe3)2(SiMe 2Ph)}2] (4). The reaction of 4 with MgBr2 gave the doubly bromide-bridged lithium-magnesium complex [Li(TMEDA)(μ-Br)2Mg{C(SiMe3)2(SiMe 2Ph)}(THF)] (6), and that of [Li(THF){C(SiMe3)2(SiMe2C5H 4N-2)}] gave the singly bridged compound [Li(THF)3(μ-Br)MgBr{C(SiMe3)2(SiMe 2C5H4N-2)] (8). The Grignard reagents [Mg{C(SiMe3)3}I(OEt2)]2 (10) and [Mg{C(SiMe3)2 (SiMe2Ph)}I(OEt2)]2 (11) were obtained from the reactions between (Me3Si)3CI and (Me2Ph)(Me3Si)CI, respectively, with magnesium metal and shown to have halide-bridged structures. The unsymmetrical dialkylmagnesium [MgBu{C(SiMe3)2(SiMe2NMe2)}(THF)] (13), was prepared from a mixture of LiBu, 1 and [MgBr2 (OEt2)2].
Polychlorinated materials as a source of polyanionic synthons
Guijarro, Albert,Yus, Miguel
, p. 1797 - 1810 (2007/10/03)
The reaction of dichloromethane (1a) or dichlorodideuteriomethane (1b) with an excess of lithium powder (1:7 molar ratio) and a catalytic amount of DTBB (5 mol%) in the presence of a carbonyl compound 2 (1:2 molar ratio) in THF at -40°C yields, after hydrolysis, the corresponding 1,3-diols 3 in moderate yields. The process is applied to other gem-dichlorinated materials such as 7,7-dichloro [4.1.0]heptane (4), 1,1-dichlorotetramethylcyclopropane (7) and dichloromethyl methyl ether (10), using pivalaldehyde as electrophile. Starting from 1,1,1-trichlorinated compounds or tetrachloromethane (14) and using chlorotrimethylsilane as electrophile at temperatures ranging between -80 and -90°C, the corresponding polysilylated compounds 15-17 are prepared applying the mentioned methodology.
Properties of Chalcogen-Chalcogen Bonds, XVII. - Di- and Trisulfanes with Sterically Congested Alkyl Substtuents: The First trans-Dialkyldisulfane
Ostrowski, Martin,Jeske, Joerg,Jones, Peter G.,Mont, Wolf-Walther du
, p. 1355 - 1360 (2007/10/02)
Bistrisulfane (1) is obtained from tris(trimethylsilyl)methyllithium and sulfur with subsequent oxidation by oxygen or from tris(trimethylsilyl)methanethiol with sulfur dichloride.The solid trisulfane contains a transoid (helical) C-S-S-S-C backbone without severe distortion from steric strain.Desulfuration of the byproduct bistetrasulfane (2) with mercury provides 1, but further desulfuration of 1 to bisdisulfane (3) has not been achieved. 3 was isolated after oxidation of lithium tris(trimethylsilyl)methanethiolate with bromine. 3 contains a trans-C-S-S-C moiety with an unusually long S-S bond (210-211 pm).The less crowded bis(triphenylmethyl)disulfane (4) contains a "normal" C-S-S-C moiety with anticlinal conformation (torsion angle -110 deg). Key Words: Disulfanes / Trisulfanes / Bond conformations, S-S
ZUR HERSTELLUNG UND REAKTIVITAET VON BIS(TRIMETHYLSILYL)DILITHIOMETHAN
Eikema Hommes, N. J. R. van,Bickelhaupt, F.,Klumpp, G. W.
, p. 5237 - 5240 (2007/10/02)
At -90 deg C in THF or similar media bis(trimethylsilyl)dichloromethane 2 reacts with lithium-4,4'-di-tert-butylbiphenyl (LiDBB) or suspensions of freshly sublimed lithium to give the title compound 1 that can bind two equivalents of various electrophiles. 1 has a great propensity for proton abstraction and it is markedly less reactive towards ethyl iodide than (Me3Si)2EtCLi 6.
Electrosynthese en chimie organosilicique: silylation selective de polychloromethanes
Pons, P.,Biran, C.,Bordeau, M.,Dunogues, J.
, p. 31 - 38 (2007/10/02)
Silylation by electroreduction of carbon tetrachloride, chloroform or methylene chloride is more selective than the common organometallic route.Me3SiCCl3 (94percent) and (Me3Si)2Cl2 (68percent) were thus obtained from CCl4, Me3SiCHCl2, (94percent) and (Me3Si)2CHCl (56percent) from CHCl3 and Me3SiCH2Cl (90percent) from CH2Cl2.Complete silylation of polychloromethanes was also successful by electrosynthesis and gave satisfactory yields.
On the Way to a Stable Silaethene Si=C : Sterically Overloaded Trisilylmethanes tBu2SiX-CY(SiMe3)2 (X, Y = H, Hal, Li)
Wiberg, Nils,Wagner, Gerhard
, p. 1455 - 1466 (2007/10/02)
Sterically overloaded trisilylmethanes tBu2SiX-CY(SiMe3)2 (X = H, Me, F, Br; Y = H, Br, Li) (3-12) are accessible via tBu2SiH-CH(SiMe3)2 (7) (from tBu2SiHF and LiCH-(SiMe3)2).The compounds are characterized by hindered rotation about the Si-C single bond shown.On gentle heating, tBu2SiF-CLi(SiMe3)2 (10) rearranges into the compound Me2SiF-CLi(SiMe3)(SiMetBu2) (14), which in turn decomposes at 100 deg C into LiF and the silaethene Me2Si=C(SiMe3)(SiMetBu2) (16).The latter, in the absence of a reactant, furnishes a mixture of secondary products and, in the presence of 1,3-butadiene, reacts to yield the Diels-Alder adduct 19.
