- The thermolysis of ε-halodisilanes: A preference for 1,2-Si Si→O rearrangement or Si-O cleavage over Si=O bond formation
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Tris(trimethylsilyl)-2,2,2-trifluoroethoxysilane 6, tris(trimethylsilyl)-2-fluoroethoxysilane 7, and tris(trimethylsilyl)-2-chloroethoxysilane 8 were synthesized and characterized by 1H, 13C and 29Si NMR, IR spectroscopy, and EI and CI mass spectrometry. Thermodynamic considerations would suggest that, as a result of the driving force provided by the formation of a Si-F or Si-Cl bond, the thermolyses of these compounds would lead to the formation of bis(trimethylsilyl)silanone 4. To examine this question, gas chromatography - mass spectrometry was as used a detection technique for products resulting from the high-pressure thermolyses of 6-8. The elimination of (Me3Si)3SiCl appears to be the major thermolytic pathway of decomposition for 8 at ambient or higher pressures, although it is accompanied by the formation of other products, some of which could have arisen from the addition of various halosilanes to a silanone. Neither 6 nor 7 thermolyzed cleanly; the former compound was essentially unreactive under the thermolysis temperatures used (850°C). Of the products produced in the thermolysis of 7, no evidence for the formation of the silanone was obtained. Independently, mass spectrometry was used to study unimolecular reactions of molecular ions derived from 6-8. The major route to solitary ions appears to involve a 1,2-trimethylsilyl migration from Si to O (9→10) prior to decomposition, for example, of the m/z 346 parent ion in the decomposition of 6. The preparation of the ionized silanone may be a minor pathway. Some of the other fragmentation pathways for 6-8 are discussed.
- Roos, Christopher,McGibbon, Graham A.,Brook, Michael A.
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- Lithium and sodium tris(trimethylsilyl)silanolates. Synthesis and reactivity
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Lithium and sodium tris(trimethylsilyl)silanolates were obtained by the reaction of tris(trimethylsilyl)silanol with BunLi or PriONa in hexane.The degree of association of silanolates in benzene solution was found to be 2 and 4 for t
- Kornev, A. N.,Chesnokova, T. A.,Semenov, V. V.,Kurskii, Yu. A.
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- Tris(trimethylsilyl)silyllithium
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An investigation has been made of the relative reactivity of tris(trimethylsilyl)silyllithium (I) in an attempt to estimate the importance of (dπ-pπ) bonding involving two contiguous silicon atoms. The procedure used were: (1) a comparative metalation reaction; (2) a kinetic study; and (3) a cleavage reaction of a silicon-silicon bond. The results are not definitive; although they seem to imply that the reactivity of I is comparable to or less than that of triphenylsilyllithium. The reactivity of I, together with its ultraviolet and NMR spectra, has been explained in terms of dative π-bonding.
- Gilman, Henry,Smith, Clifford L.
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- Synthesis, characterization and reactivity of yttrium and gadolinium silyl complexes
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The syntheses of yttrium and gadolinium-silyl complexes of the form R(Me3Si)2SiMI2(THF)3 (M = Y, Gd; R = Et, SiMe3) through reactions of potassium silyl reagents, KSiR(SiMe3)2(TH
- Sgro, Michael J.,Piers, Warren E.
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- TRIS(TRIMETHYLSILYL)SILANE:A CATALYST FOR RADICAL MEDIATED REDUCTION REACTIONS
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Tris(trimethylsilyl)silane was an effective substitute for toxic, tributyltin hydride in free radical chain reductions of organic halides.It was used in catalytic amounts and was regenerated, in situ, by using sodium borohydride.
- Lesage, M.,Chatgilialoglu, C.,Griller, D.
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- Process for preparing tetrakis (trimethylsily) silane and tris (trimethysilyl) silane
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Tetrakis(trimethylsilyl)silane is prepared by reacting tetrachlorosilane with chlorotrimethylsilane in the presence of lithium metal, adding a compound with active proton(s) to the reaction mixture for treating the residual lithium metal therewith while maintaining the mixture neutral or acidic, and separating tetrakis(trimethylsilyl)silane from the organic layer. The residual lithium metal is treated in a safe and simple manner. Reaction of the tetrakis(trimethylsilyl)silane with an alkyl lithium or alkali metal alkoxide, followed by acid hydrolysis, affords tris(trimethylsilyl)silane. The desired compounds are prepared in high yields and on an industrial scale.
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- A new and easy route to polysilanylpotassium compounds
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A method is presented for the synthesis of tertiary, secondary, and primary polysilylpotassium compounds. Reaction of potassium tert-butoxide, in either DME or THF, with a suitable precursor molecule, proceeds by cleavage of a trimethylsilyl - polysilanyl bond, and formation of trimethylsilyl tert-butyl ether and a polysilanylpotassium compound. This route allows easy and flexible access to a number of novel polysilanylpotassium compounds, avoiding the hitherto common use of poisonous mercury compounds.
- Marschner, Christoph
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p. 221 - 226
(2007/10/03)
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- Reactions of (η5-C5H5)(η5-C5Me5)ZrX (X = Cl, Me) complexes with carbon monoxide and the isocyanide 2,6-Me2C6H3NC. Crystal structure of (η5-C5H5)(η5C5Me5)Zr2-C(N-2,6-Me2C6H3)Si(SiMe3)3>Cl
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The new tris(trimethylsilyl)silylzirconium derivative (η5-C5H5)(η5-C5Me5)ZrCl (1) is prepared by reaction of (Η5-C5H5)(η5-C5Me5)ZrCl2 with (THF)3LiSi(SiMe3)3.Mixed alkyl/silyl complex (η5-C5H5)(η5-C5Me5)ZrMe (2) is obtained after treatment of 1 with MeMgBr.Reactions of compounds 1 and 2 with carbon monoxide and 2,6-Me2C6H3NC are described.Carbon monoxide inserts cleanly into the Zr-Si bond of 1, giving the η2-silaacyl (η5-C5H5)(η5-C5Me5)Zr2-COSi(SiMe3)3>Cl (3).The reaction of 2 with CO proceeds via the intermediate (η5-C5H5)(η5-C5Me5)Zr2-COSi(SiMe3)3>Me (4) to the enolate hydride (η5-C5H5)(η5-C5Me5)ZrH (5).A mechanism for this rearrangement is proposed.This chemistry contrasts with that previously observed for (η5-C5H5)2ZrMe, which reacts with CO to cleanly give the stable acyl (η5-C5H5)2Zr(η2-COMe).Methyl iodide and compound 5 react to give the iodide (η5-C5H5)(η5-C5Me5)ZrI (6) and methane.The reaction of 5 with 2 equivalents of HCl provides a new synthetic route to an acysilane MeCOSi(SiMe3)3.Reactions of 1 and 2 with the isocyanide 2,6-Me2C6H3NC give the insertion products (η5-C5H5)(η5-C5Me5)Zr2-C(N-2,6-Me2C6H3)Si(SiMe3)3>Cl (7) and (η5-C5H5)(η5-C5Me5)Zr2-C(N-2,6-Me2C6H3)-Me>Si(SiMe3)3 (8), respectively.Steric crowding in these compounds is evidenced by restricted rotation about the N-C(xylyl) bonds.An X-ray crystal structure of 7 has been determined.Crystals of 7 are monoclinic, P21/c, with a 18.276(6) Angstroem, b 9.993(3) Angstroem, c 21.550(5) Angstroem, β 106.25(3) deg; V 3779(2) Angstroem3, Z = 4, RF 6.63percent RwF 6.48percent.
- Elsner, Frederick H.,Tilley, T. Don,Rheingold, Arnold L.,Geib, Steven J.
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p. 169 - 184
(2007/10/02)
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