54008-64-9Relevant academic research and scientific papers
Adducts of sila-, germa-, and stannaethenes Me2E=C(SiMe3)2 (E = Si, Ge, Sn) with anthracene: Syntheses, structures, thermolyses
Wiberg, Nils,Wagner, Susanne,Vasisht, Sham-Kumar,Polborn, Kurt
, p. 1412 - 1420 (2007/10/03)
The [4 + 2] cycloadducts of Me2E=C(SiMe3)2 (E = Si, Ge, Sn) and anthracene are prepared by reaction of an excess of anthracene in benzene with the [2 + 2] cycloadduct of Me2Si=C(SiMe3)2 and Ph2C=NSiMe
Dimere der Ethene Me2E=C(SiMe3)2 (E=Si, Ge, Sn): Auf welchem Wege entstehen sie aus Me2EX-CM(SiMe3)2? Wie sind sie strukturiert?
Wiberg,Passler,Wagner,Polborn
, p. 292 - 303 (2007/10/03)
Alkali metal organyls or silyls MR (e.g. LiMe, LinBu, LitBu, LiPh, LiCH(SiMe3)2, LiC(SiMe3)3, NaSitBu3) convert equimolar amounts of bromomethanes Me2EX-CBr(SiMe3)2 with E=Si, Ge, Sn and electronegative substituents X (e.g. F, Br, OPh) in organic solvents (e.g. pentane, diethyl ether, tetrahydrofuran) (i) by a very fast Br/M exchange into the 'metalation products' Me2EX-CM(SiMe3)2, which thermolyze under formation of 'cyclobutanes' [-Me2E-C(SiMe3)2-]2, and (ii) to a lesser extent by X/R exchange into 'substitution products' Me2ER-CBr(SiMe3)2. As shown by trapping experiments, the unsaturated compounds Me2E=C(SiMe3)2 play the role of short-lived intermediates in both reactions. They are formed from Me2EX-CM(SiMe3)2 by MX elimination and add the present alkalimetal compounds Me2EX-CM(SiMe3)2≡MR′ or MR, respectively. The products Me2ER′-CM(SiMe3)2 with R′=C(EXMe2)(SiMe3)2, obtained in this way, eliminate MX under formation of the mentioned 'cyclobutanes'. On the other hand, the compounds Me2ER-CM(SiMe3)2 convert unreacted Me2EX-CBr(SiMe3)2 in Me2EX-CM(SiMe3)2 under formation of Me2ER-CBr(SiMe3)2. Relative rates of both the metalation reactions and the salt eliminations are determined. X-ray structure analyses of [-Me2E-C(SiMe3)2-]2 (E=Si, Ge, Sn) prove their 1,3-dielementacyclobutane structure with planar four-membered ECEC rings.
Storing of the Labile Silaethene Me2Si=C(SiMe3)2 with N-Trimethylsilyl-benzophenoneimine Ph2C=NSiMe3
Wiberg, Nils,Preiner, G.,Wagner, G.,Koepf, H.,Fischer, G.
, p. 1055 - 1061 (2007/10/02)
N-Trimethylsilyl-benzophenoneimine Ph2C=NSiMe3 is able to "store" the silaethene Me2Si=C(SiMe3)2 (1), produced from Me2SiF-CLi(SiMe3)2, under formation of a - and -cycloadduct (2, 3), respectively.Above 60 deg C (above 120 deg C) 2 or 3 by the way of 1 transform into 1:5 mixture of 2 and 3 (into a 1:1 mixture of the dimer of 1 and the insertion product of 1 into the SiN-bond of Ph2C=NSiMe3).In the presence of 2,3-dimethyl-1,3-butadiene (dmb), 2 or 3 form by way of the reaction of the intermediate 1 with dmb a -cycloadduct (75percent) and an ene reaction product (25percent).The rate constants of the first order decomposition of 2 or 3 in the presence of dmb (80 deg C, solvents like Et2O, C6H6) are in the order of 2 E-4 s-1 (τ1/2 ca. 1 h) and 3 E-5 s-1 (τ1/2 ca. 6 h), respectively. - Key words: Silaethene Me2Si=C(SiMe3)2, Ph2C=NSiMe3-adduct, Kinetic Studies
Reaktivitaet des Silaethens Me2Si=C(SiMe3)2: Thermolyse von (Me3Si)2(Me2XSi)CLi (X z. B. (PhO)2PO2) in Anwesenheit von Silaethen-Faengern
Wiberg, Nils,Preiner, Gerhard,Schieda, Oswald
, p. 3518 - 3532 (2007/10/02)
Silaethene Me2Si=C(SiMe3)2 (1), generated as a reaction intermediate by the thermal elimination of LiX from Me2XSi-CLi(SiMe3)2, combines with the reactants a - b (e. g.Me3Si-Cl, Me3Si-OMe) with insertion in the a - b bond, with a = b - c - H (e. g.CH2=CMe
On the Way to Silaethene Me2Si=C(SiMe3)2: Trisilylated Methanes (Me3Si)2(Me2XSi)CY (X=e. g. Hal, RO, RS; Y e. g. Br, Li)
Wiberg, Nils,Preiner, Gerhard,Schieda, Oswald
, p. 2087 - 2103 (2007/10/02)
Bromotrisilylmethanes (Me3Si)2(Me2XSi)CBr (1 - 15) are formed as a result of the reaction of (Me3Si)2(Me2PhSi)CBr (16) with iodine monochloride, bromine and iodine (X = Cl, Br, I) respectively, and also through the reaction of (Me3Si)2(Me2BrSi)CBr (1) with AgX (X = F, p-TolSO2, p-TolSO3, MesSO3, Ph2PO2, Ph2PO3, Ph2PO4) or MX (M = H, Li, Na; X = HO, RO, RS, Bu, Ph).Butyl- as well as phenyllithium convert bromotrisilylmethanes 1 - 16 at low temperatures into lithium derivatives (Me3Si)2(Me2XSi)CLi (1a - 16a).These are in some cases (X = R, RO) thermostable, whereas, in other cases they decompose more or less readily under LiX elimination and lead (in many cases via silaethene Me2Si=C(SiMe3)2) to the disilacyclobutane derivative 2 (17).Acids HZ (e. g.HCl, HOMe, Me3CBr) protonate the lithium compounds into (Me3Si)2(Me2XSi)CH as well as (Me3Si)2(Me2ZSi)CH.Butyl bromide converts the more stable lithium compounds (Me3Si)2(Me2XSi)CLi (X = R, RO, F, Ph2POn) into butyl derivatives (Me3Si)2(Me2XSi)CBu.
Erzeugung und Nachweis des Silaethens Me2Si=C(SiMe3)2: Thermischer Zerfall von (Me3Si)2(Me2XSi)CLi (X z. B. Hal, OR, SR)
Wiberg, Nils,Preiner, Gerhard,Schieda, Oswald,Fischer, Gerd
, p. 3505 - 3517 (2007/10/02)
Thermal decomposition of Me2XSi-CLi(SiMe3)2 (1,LiX) in diethyl ether at -102 to 10 deg C leads under intramolecular LiX-elimination (X = Hal, TosO, Ph2POn, PhS) to 1,3-disilacyclobutane 2 (2).The reactive intermediate product is the silae
