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Do T Tilley - One of the best experts on this subject based on the ideXlab platform.
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lewis acidity of bis perfluorocatecholato silane aldehyde hydrosilylation catalyzed by a neutral Silicon Compound
ChemInform, 2015Co-Authors: Allegra L Libermanmarti, Robe G Ergma, Do T TilleyAbstract:The novel Lewis acid catalyst bis(perfluorocatecholato)silane (BPS) is prepared and applied to the hydrosilylation of electron-deficient aldehydes.
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lewis acidity of bis perfluorocatecholato silane aldehyde hydrosilylation catalyzed by a neutral Silicon Compound
Journal of the American Chemical Society, 2015Co-Authors: Allegra L Libermanmarti, Robe G Ergma, Do T TilleyAbstract:Bis(perfluorocatecholato)silane Si(catF)2 was prepared, and stoichiometric binding to Lewis bases was demonstrated with fluoride, triethylphosphine oxide, and N,N′-diisopropylbenzamide. The potent Lewis acidity of Si(catF)2 was suggested from catalytic hydrosilylation and silylcyanation reactions with aldehydes. Mechanistic studies of hydrosilylation using an optically active silane substrate, R-(+)-methyl-(1-naphthyl)phenylsilane, proceeded with predominant stereochemical retention at Silicon, consistent with a carbonyl activation pathway. The enantiospecificity was dependent on solvent and salt effects, with increasing solvent polarity or addition of NBu4BArF4 leading to a diminished enantiomeric ratio. The medium effects are consistent with an ionic mechanism, wherein hydride transfer occurs prior to Silicon–oxygen bond formation.
Jacek Klinowski - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of zeolites from sodium silicoglycolate, a 5-coordinate Silicon Compound
Chemical Physics Letters, 1994Co-Authors: Bruno Herreros, Jacek KlinowskiAbstract:Abstract We have used sodium silicoglycolate, an organoSilicon Compound in which Si is in 5-coordination with respect to oxygen, to prepare the molecular sieve silicalite as well as sodalites of different compositions. The highly reactive 5-coordinate Silicon Compounds are promising starting materials for the synthesis of Silicone polymers, molecular sieves, glasses, semiconductors and ceramics.
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Spectroscopic Studies of 5-Coordinate Silicon Compounds
The Journal of Physical Chemistry, 1994Co-Authors: Bruno Herreros, Tery L. Barr, Patrick J. Barrie, Jacek KlinowskiAbstract:A detailed study of the structural and chemical features of a series of novel Compounds in which Silicon is in 5-coordination with respect to oxygen has been carried out using XRD, FTIR, solid-state NMR, and ESCA. All Compounds contain glycolate groups and different charge-balancing alkali-metal cations. NMR confirms that only 5-coordinate Si is present. There is a unique set of ESCA core level binding energies for these materials. Peak positions may be influenced by (1) the coordination number of Si, (2) the presence of organic moieties, and (3) the kind and concentration of cations. All binding energies in the 5-coordinate Silicon Compound with Cs + are shifted with respect to those in other Compounds to suggest that effects (1) and (3) are dominant
Mathias S Wickleder - One of the best experts on this subject based on the ideXlab platform.
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reactions with oleum under harsh conditions characterization of the unique m s2o7 3 2 ions m si ge sn in a2 m s2o7 3 a nh4 ag
Chemistry: A European Journal, 2012Co-Authors: Christian Logemann, Daniel Gunzelmann, Thorsten Kluner, Jurgen Senker, Mathias S WicklederAbstract:The reactions of group 14 tetrachlorides MCl4 (M=Si, Ge, Sn) with oleum (65 % SO3) at elevated temperatures lead to the unique complex ions [M(S2O7)3]2−, which show the central M atoms in coordination with three chelating S2O72− groups. The mean distances MO within the anions increase from 175.6(2)–177.5(2) pm (M=Si) to 186.4(4)–187.7(4) pm (M=Ge) to 201.9(2)–203.5(2) pm (M=Sn). These distances are reproduced well by DFT calculations. The same calculations show an increasing positive charge for the central M atom in the row Si, Ge, Sn, which can be interpreted as the decreasing covalency of the MO bonds. For the Silicon Compound (NH4)2[Si(S2O7)3], 29Si solid-state NMR measurements have been performed, with the results showing a signal at −215.5 ppm for (NH4)2[Si(S2O7)3], which is in very good agreement with theoretical estimations. In addition, the vibrational modes within the [MO6] skeleton have been monitored by Raman spectroscopy for selected examples, and are well reproduced by theory. The charge balance for the [M(S2O7)3]2− ions is achieved by monovalent A+ counter ions (A=NH4, Ag), which are implemented in the syntheses in the form of their sulfates. The sizes of the A+ ions, that is, their coordination requirements, cause the crystallographic differences in the crystal structures, although the complex [M(S2O7)3]2− ions remain essentially unaffected with the different A+ ions. Furthermore, the nature of the A+ ions influences the thermal behavior of the Compounds, which has been monitored for selected examples by thermogravimetric differential thermal analysis (DTA/TG) and XRD measurements.
Guo Jingguo - One of the best experts on this subject based on the ideXlab platform.
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lubricative water based metal surface treatment agent and metal surface treatment method using the same
2015Co-Authors: Guo JingguoAbstract:The invention relates to a lubricating water-based metal surface treatment agent and a metal surface treatment method using the same. The lubricating water-based metal surface treatment agent comprises a water-based chromium-free composition, a water-soluble or water-dispersible organic resin and a wax additive. The water-based chromium-free composition comprises a water-soluble zirconium Compound, a Silicon Compound, a fluorine containing Compound, a phosphoric acid Compound and a metal Compound. The ratio of a solid component of the organic resin to the overall solid component is between 0.01 to 0.9. The ration of a solid component of the wax additive to the overall solid component is between 0.005 to 0.03. Thereby a metal material having the lubricating water-based metal surface treatment agent can have good corrosion resistance, alkali washable performance, lubricity and wear resistance.
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aqueous metal surface treatment agent and metal surface treatment method employing the treatment agent
2013Co-Authors: Guo JingguoAbstract:The invention relates to an aqueous metal surface treatment agent and a metal surface treatment method employing the treatment agent. The aqueous metal surface treatment agent comprises a water-soluble zirconium Compound, a Silicon Compound, a fluorinated Compound, a phosphate Compound and a metallic Compound. The mass ratio of the Silicon Compound to the water-soluble zirconium Compound is 0.5 to 2.0, the fluorinated Compound has at least one fluoride group, the mass ratio of the fluorinated Compound and the water-soluble zirconium Compound is from 0.2 to 1.0, and the mass ratio of the phosphate Compound to the water-soluble zirconium Compound is from 0.2 to 0.7, and the mass ratio of the metallic Compound to the water-soluble zirconium Compound is from 0.2 to 0.6. Thereby, the metal material processed by the aqueous metal surface treatment agent is corrosion resistant, alkali washing resistant, blackening resistant and fingerprint resistant.
Allegra L Libermanmarti - One of the best experts on this subject based on the ideXlab platform.
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lewis acidity of bis perfluorocatecholato silane aldehyde hydrosilylation catalyzed by a neutral Silicon Compound
ChemInform, 2015Co-Authors: Allegra L Libermanmarti, Robe G Ergma, Do T TilleyAbstract:The novel Lewis acid catalyst bis(perfluorocatecholato)silane (BPS) is prepared and applied to the hydrosilylation of electron-deficient aldehydes.
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lewis acidity of bis perfluorocatecholato silane aldehyde hydrosilylation catalyzed by a neutral Silicon Compound
Journal of the American Chemical Society, 2015Co-Authors: Allegra L Libermanmarti, Robe G Ergma, Do T TilleyAbstract:Bis(perfluorocatecholato)silane Si(catF)2 was prepared, and stoichiometric binding to Lewis bases was demonstrated with fluoride, triethylphosphine oxide, and N,N′-diisopropylbenzamide. The potent Lewis acidity of Si(catF)2 was suggested from catalytic hydrosilylation and silylcyanation reactions with aldehydes. Mechanistic studies of hydrosilylation using an optically active silane substrate, R-(+)-methyl-(1-naphthyl)phenylsilane, proceeded with predominant stereochemical retention at Silicon, consistent with a carbonyl activation pathway. The enantiospecificity was dependent on solvent and salt effects, with increasing solvent polarity or addition of NBu4BArF4 leading to a diminished enantiomeric ratio. The medium effects are consistent with an ionic mechanism, wherein hydride transfer occurs prior to Silicon–oxygen bond formation.