- Plasmochemical synthesis of thin layers of the sulfur doped silicon dioxide
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Plasmochemical synthesis of thin layers of the sulfur atoms doped SiO 2 on the basis of volatile Siorganoelement compounds containing the Si-S fragments was studied. Highly pure trimethyl-ethylthiosilane Me 3SiSEt was used as a precu
- Mirskov,Rakhlin,Adamovich,Voronkov
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- Spin chemistry of organometallic compounds: Part 1. Interaction of N-bromohexamethyldisilazane with allyltriethylstannane
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It has been shown, on the basis of the analysis of CIDNP effects, that allene and (Me3Si)2NH - major products of the photoinduced reaction of Et3SnCH2CH=CH2 and (Me3Si)2NBr - result from a radical pair comprised of ·CH2CHBrCH2SnEt3 and ·N(SiMe3)2 free radicals. Allene is formed through the β-cleavage of the short-lived homolytic substitution product Et3SnCH2CBr=CH2.
- Taraban, Marc B.,Kruppa, Alexander I.,Rakhlin, Vladimir I.,Grigor'Ev, Stanislav I.,Volkova, Olga S.,Mirskov, Rudolph G.,Leshina, Tatyana V.
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- AN INVESTIGATION OF THE MECHANISM OF THE REACTION OF ALLYLTRIETHYLSTANNANE WITH BROMOTRICHLOROMETHANE BY RADIOFREQUENCY PROBING AND CHEMICALLY INDUCED DYNAMIC NUCLEAR POLARIZATION (CIDNP)
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The methods of radiofrequency probing (RFP) and chemcally induced dynamic nuclear polarization (CIDNP) have been used to study the mechanism of the reaction of allyltriethylstannane with bromotrichloromethane.The CIDNP effects which have been detected prove the presence of radical stages in this reaction.An assumption has been made about a possible radical pathway for the β-decomposition of elementorganic compounds.
- Leshina, T.V.,Sagdeev, R.Z.,Polyakov, N.E.,Taraban, M.B.,Valyaev, V.I.,et al.
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- Homolytic reactions of N-bromohexamethyldisilazane with trialkyl(phenylalkoxy) derivatives of silicon and tin
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The main product of the photoinduced reaction of N- bromohexamethyldisilazane with trialkyl-(benzyloxy)derivatives of silicon and tin R3MO(CH2)nPh (R = Me, Et; M = Si, Sn; n = 1) is N,N-dibenzylidene-C-phenylmethanediamine (hydrobenzamide). For M = Si, with increase of the length of the methylene chain between the oxygen atom and the phenyl group (n = 2, 3), the similar reaction affords the product of bromination of the benzylic carbon atom R3MO(CH2) n-1CHBrPh. For M = Sn, the reaction results in the formation of 2-phenyloxacycloalkanes PhCHO(CH2)n-1. Pleiades Publishing, Ltd., 2010.
- Rakhlin,Podgorbunskaya,Voronkov
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p. 930 - 935
(2011/01/09)
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- Homolytic addition of polyhaloalkanes to α-vinyloxy-ω-trialkylstannoxyalkanes as a new route to 2-perhaloalkylmethyl-substituted 1,3-dioxacyclanes
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Photoinduced reactions of α-vinyloxy-ω-trialkylstannoxyalkanes, CH2=CHO(CH2)nOSnEt3 (n = 2 to 4), with polyhaloalkanes results in 2-perhaloalkylmethyl-substituted 1,3-dioxacyclanes. - Key words: α-vinyloxy-ω-trialkylstannoxyalkanes, polyhaloalkanes, photoinduced reactions; 1,3-dioxacyclanes.
- Arbuzov, P. V.,Voronkov, M. G.,Mirskov, R. G.,Stankevich, V. K.,Kukharev, B. F.,et al.
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p. 1755 - 1757
(2007/10/03)
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- Selective and sequential reduction of polyhalosilanes with alkyltin hydrides
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The reactions between alkyltin hydrides and a variety of polyhalo- and mixed halosilanes have been investigated. For SiCl4 and SiCl3H, the reductions proceed in a stepwise manner to yield the monoreduced species as the major products. The reduction of SiBr4 occurs much faster to yield a mixture of SiBr3H and SiH4, or, in the vapor phase, SiBr3H as the sole product. SiF3X (X = Br, Cl) is converted into SiF3H, with no further reduction of SiF3H observed upon addition of a second equivalent of alkyltin hydride. SiF2HX compounds (X = Br, Cl) are obtained from SiF2X2 and are converted into SiF2H2 with excess Me3SnH. Redistribution becomes competitive with reduction in reactions between Me3SnH and SiFBr3, leading to mixtures of SiH4, SiF2H2, and SiF3H. The major products in the reaction between SiCl2Br2 and Me3SnH are SiCl3H and SiH4 (no SiCl2H2 was observed). Several probable intermediates were independently synthesized and allowed to react with Me3SnH. Together with deuterium labeling experiments, these reactions shed light on the mechanisms involved in these systems. In particular, the reactions appear not to proceed via free radicals.
- D'Errico, John J.,Sharp, Kenneth G.
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p. 2177 - 2180
(2008/10/08)
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- Charge transfer spectra of organometallic complexes II. Determination of the donor site in trialkyltinhalides
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The charge transfer spectra of several trialkyltiniodide- and bromide-iodine systems are presented.Interpretation of the blue shift, the charge transfer band maximum and the formation constant data leads to the conclusion that, on complexation with iodine
- Verdonck, L.,Hoste, S.,Herman, G. G.,Lippens, W.,Kelen, G. P. van der
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p. 215 - 218
(2007/10/02)
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- METAL-HALOGEN BONDING STUDIES WITH GROUP IV A TRIALKYLMETAL HALIDES
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Halogen redistribution reactions have been found to take place between benzyl bromide or benzyl iodide and the Group IV A silicon, germanium, tin, and lead containing trialkylmetal chlorides.However, for the reactions of the Si, Ge and Sn compounds, a quaternary ammonium halide catalyst was necessary to enable the equilibria to be established at reasonably rapid rates.The equilibrium constants at 50 deg C have been measured for each of these halogen redistributions.They have been found to increase gradually on going down in Group IV A from silicon to lead, being conside rably less than unity in the case of silicon and somewhat greater than unity in the case of lead for both the R3MCl + BzBr and R3MCl + BzI reactions.The ΔG0 values for these equilibria have been calculated, and it is suggested that their differences may be explained in terms of the relative importance of p?-d? contributions to the halogen-metal bonding in the various Group IV A trialkylmetal halide systems.
- Friedrich, Edwin C.,Abma, Charles B.,Vartanian, Paul F.
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p. 203 - 212
(2007/10/02)
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- Electron Donor-Acceptor Complexes. 1. Linear Free Energy Correletion of the Charge-Transfer Transition Energy with the Kinetics of Halogenolysis of Alkylmetals
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Mulliken charge-transfer theory is used to relate the properties of transient donor-acceptor complexes between alkylmetals and halogens with the kinetics of the accompanying cleavage reaction (halogenolysis).The formulation derives from the charge-transfer transition energy hνCT which is proportional to the second-order rate constant for halogenolysis of a variety of tetraalkyltin compounds in hexane or carbon tetrachloride solutions.The description of the activation process for halogenolysis as an electron transfer in the CT complex, e.g., --> , leads to a linear free energy relationship in which the activation free energy is equal to the driving force for ion pair formation.The latter is equated to the charge-transfer transition energy plus a contribution from the solvation energy, by employing a comparative procedure for the evaluation of alkylmetals.An independent measure of the solvation energy obtained from the gas-phase ionization potentials of alkylmetals and their free energy changes in solution supports the electron-transfer formulation of the activation process.The charge-transfer mechanism is generalized for the halogenolysis of alkylmetals.
- Fukuzumi, S.,Kochl, J.K.
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p. 2246 - 2254
(2007/10/02)
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- Mechanisms for the cleavage of carbon-tin bonds. VI. A kinetic and stereochemical study of the halodemetallation of cyclopropyltrialkyltins: the solvent effect
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The bimolecular halodemetallation of substituted cyclopropyltrialkyltins is stereospecific, and proceeds with retention of the configuration at carbon in methanol, acetic acid and chlorobenzene. The kinetic study confirms the hypothesis which was based on results for the R′SnR3 series, and shows the participation of the ring orbitals in the rate determining step of the reaction. A study of the selectivity in various media has revealed a surprising solvent effect.
- Gielen,Baekelmans,Nasielski
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p. 329 - 339
(2008/10/08)
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- Mechanisms of the rupture of the carbon-tin bond by halogens I. Electrophilic substitution at a saturated carbon atom
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The reaction between halogens and tetraalkyltins is strongly influeced by the dielectric constant, the polarisability and the nucleophilicity of the solvent. These three aspects of solvent action are relatd to the ability of tin to make use of its empty 5d orbitals: the Sn polarisation, enhanced by the pentaco-ordination of the metal, governs the reactivity of the alkyl groups attached to it, appropriate attention being given to the incursion of steric effects. In polar media, the solvent itself acts as the nucleophilic catalyst and the reaction is best described by the following scheme {A figure is presented}. In less active solvents, the halogen molecule plays the role of nucleophile in a predetermining step the most likely mechanism may be written as follows: {A figure is presented}.
- Boue, S,Gielen, M,Nasielski, J
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p. 443 - 460
(2007/10/18)
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- Mechanisms of the rupture of the carbon-tin bond by halogens II. Free-radical substitution in solution
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The experiments describes in this paper show that the light-induced bromodemetallation of tetraalkyltins in chlorobenzene is a free radical substitution on tin, followed by a propagation step: {A figure is presented}. The stabilisation of R? by hyperconjugation seems to be an important factor for the reaction, but there is evidence for the influence of the other three substituents of tin and of the nature of the attacking radical on the reaction mechanism. The relation between the strucutre and the reactivity of tetraalkyltins suggests that the carbon-tin bond is only slightly loosened in the transition state; this agrees with the great reactivity of the Br atom.
- Boue, S,Gielen, M,Nasielski, J
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p. 461 - 479
(2008/10/08)
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