- Unusually selective synthesis of chlorohydrooligosilanes
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New pathways towards molecular chlorohydrooligosilanes enable their one-pot synthesis in preparative amounts either by the selective chlorination of the corresponding perhydrosilanes with HCl/AlCl3 or by the partial hydrogenation of perchlorooligosilanes
- Lainer, Thomas,Fischer, Roland,Leypold, Mario,Holthausen, Michael,Wunnicke, Odo,Haas, Michael,Stueger, Harald
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supporting information
p. 13812 - 13815
(2020/11/18)
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- Syntheses and Molecular Structures of Liquid Pyrophoric Hydridosilanes
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Trisilane, isotetrasilane, neopentasilane, and cyclohexasilane have been prepared in gram scale. In-situ cryo crystallization of these pyrophoric liquids in sealed capillaries on the diffractometer allows access to the single crystal structures of these c
- B?hme, Uwe,Franze, Georg,Friebel, Mike,Gerwig, Maik,Gründler, Franziska,Kroke, Edwin,Rosenkranz, Marco,Schmidt, Horst
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p. 762 - 773
(2020/08/05)
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- Synthesis of polysilanes by tunneling reactions of H atoms with solid Si2H6 at 10K
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Tunneling reactions of H atoms with solid Si2H6 at 10K were investigated. The in situ and real-time reactions H + Si 2H6 to form silane and polysilanes were monitored using FT-IR. Quantitative analysis of gaseou
- Sogoshi, Norihito,Sato, Shoji,Takashima, Hideaki,Sato, Tetsuya,Hiraoka, Kenzo
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p. 986 - 987
(2012/09/22)
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- Silane-phenol compound, overcoat formulation, and electrophotographic imaging member
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Provided are a silane-phenol compound, a crosslinked silxoane-phenolic protective overcoat layer thereof, and an electrophotographic imaging member such as photoreceptor. The silane-phenol compound comprises (i) a phenol group and (ii) a silane group selected from the group consisting of alkoxysilyl, arylalkoxysilyl, aryloxysilyl, alkylaryloxysilyl, and combination thereof. The silicone overcoat is made from a formulation comprising the silane-phenol compound and a hydroxymethylated hole transport compound. The crosslinked siloxane-phenolic overcoat may be used to manufacture an electrophotographic imaging member such as photoreceptor with improved properties such as abrasive resistance, good image quality and cleanability, etc.
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- Diagnostics of the gas-phase thermal decomposition of Si2H6 using vacuum ultraviolet photoionization
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Vacuum ultraviolet (VUV) photoionization at 10.2 eV was employed for the detection of gas-phase molecules formed after thermal decomposition of disilane at a total pressure of 30 Torr and in the temperature range of 298-740 K. The SinH2(n+1) (n=3-5) and SinH2n (n=2-5) species resulting from disilane pyrolysis in a flow reactor were directly observed using time-of-flight mass spectrometry. Unlike multiphoton ionization at 6.4 eV photons, no fragmentation was observed by the VUV single-photon ionization at 10.2 eV.
- Tonokura, Kenichi,Murasaki, Tetsuya,Koshi, Mitsuo
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p. 507 - 511
(2008/10/08)
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- Molecular Structures and Conformational Composition of Trisilane and Tetrasilane by Gas-Phase Electron Diffraction
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The gas-phase electron diffraction patterns of trisilane and normal tetrasilane have been recorded with an all-glass inlet system and a nozzle temperature of 23 +/- 2 deg C.The molecular structure of trisilane was optimized and the valence force field calculated by ab initio MO calculations at the 6-31G**/MP2 level, and the structures and valence force fields of anti and gauche conformers of tetrasilane were calculated at the 6-31G*/SCF level.The force fields were scaled and used to calculate root mean-square vibrational amplitudes and correction terms for molecular vibrations.Refinement of a geometrically consistent ra-structure of Si3H8 yielded a Si-Si bond distance of ra=233.2(2) pm and a valence angle of aSiSiSi=110.2(4)o.Refinements of a mixture of geometrically consistent ra-models of gauche and anti conformers of Si4H10 yielded the bond distances (ra) Si(1)-Si(2)=233.5(3) and Si(2)-Si(3)=234.0(3) pm and the valence angle aSiSiSi=109.6o.The mole fraction of the gauche conformer was χ=68(9)percent corresponding to a free energy difference of 0.2(1.1) kJ mol-1 in favor of gauche.Introduction of the thermal vibration correction terms of tetrasilane calculated from the scaled quantum-mechanical force field led to significantly poorer agreement between experimental and calculated intensities.
- Haaland, Arne,Rypdal, Kristin,Stueger, Harald,Volden, Hans V.
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- Dehydrogenative Build-up Reactions to Silyl-Substituted Alkali Metal Germanides, Stannides, and Phosphides; Molecular Structure of Neopentasilane
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The build-up reaction between monosilane and dispersed sodium or potassium in diethyleneglycol dimethyl ether leads to alkali metal silylsilanides of the composition (Na/K)SiH3-n(SiH3)n (n = 0-3) (1, 1a-c; 2, 2a-c).By subsequent reactions with silyl nonafluorobutanesulfonate, C4F9SO3SiH3, benzenesulfonic acid, PhSO3H, and methyl p-toluenesulfonate the corresponding silanes SiH4-n(SiH3)n (n = 0-4) (3, 3a-d) and methylsilanes CH3SiH3-n(SiH3)n (n = 0-3) (4a-d) were obtained in good yield.The molecular structure of neopentasilane (3d) has been determined by electron diffraction analysis.Treatment of group IV and V hydrides GeH4, PH3, and SnH4 with mixtures of sodium or potassium silylsilanides (1, 1a-c; 2, 2a-c) leads to silyl-substituted sodium or potassium germanides (Na/K)GeH3-n(SiH3)n (n = 1-3) (5a-c, 6a-c), phosphides KPH2-n(SiH3)n (n = 1-2) (7a-b), and stannides NaSnH3-n(SiH3)n (n = 1-3) (8, 8a-c). - Key Words: Alkali metal silylsilanides / Alkali metal silylgermanides / Sodium silylstannides / Potassium silylphosphides / Neopentasilane / Electron diffraction
- Lobreyer, Thomas,Sundermeyer, Wolfgang,Oberhammer, Heinz
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p. 2111 - 2116
(2007/10/02)
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- Role of Silylene in the Deposition of Hydrogenated Amorphous Silicon
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The role of silylene in the laser deposition of hydrogenated amorphous silicon has been studied with laser-induced fluorescence and deposition rate measurements.The rate constants of the reactions of silylene and disilane and of the reverse reactions have been determined.The results show that silylene is rapidly consumed, exhibiting only a small effective lifetime.It proves that generally silyllene hardly be able to reach the surface to form amorphous silicon.The comparison of the kinetic data with the deposition rates shows that in IR laser CVD silylene starts the gas-phase chemistry and that disilene is the main film-forming molecule.The UV laser process starts with a different primary dissociation leading to silylene, which also rearranges to the film-forming disilene.
- Dietrich, Thomas R.,Chiussi, Stefano,Marek, Michael,Roth, Angelika,Comes, Franz J.
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p. 9302 - 9310
(2007/10/02)
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- Absolute rate constants for the reaction of silylene with hydrogen, silane, and disilane
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Absolute rate constants for the reaction of silylene with hydrogen, silane, and disilane have been determined from direct time resolved measurements of silylene removal at room temperature.Silylene was generated and detected using laser resonance absorption flash kinetic spectroscopy.The rate constants are pressure dependent, consistent with expectations for the insertion reactions typical of silylene.The pressure dependence of the overall rate constants has been determined from 1 to 100 Torr for reaction with hydrogen and silane and from 1 to 10 Torr for reaction with disilane.The results for reaction with hydrogen and silane have been successfully modeled using RRKM theory and high pressure bimolecular rate constants have been extracted.The rate constants detrmined in this work are significantly (10-104 times) faster than those calculated from literature values for the Arrhenius parameters.These findings require a significant upward revision in the heat of formation of silylene, and may require modification of chemical vapor deposition mechanism in which silylene is invoked as a film growth precursor.
- Jasinski, Joseph M.,Chu, Jack O.
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p. 1678 - 1687
(2007/10/02)
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- Decomposition channels of chemically activated disilane. The π bond energy of disilene and its derivatives
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The Hg (3P1) sensitized photolysis of an H2/SiH4 mixture not only yields Si2H6 but also Si3H8 and Si4H10. The formation of the latter two products as well as parts of the Si2H6 yield is explained by the decomposition of chemically activated disilane, formed by the combination of two silyl radicals. The activated disilane decomposes mainly into SiH2 + SiH4 which finally reacts to Si2H6 and to a lesser extent into H2 + H3SiSiH: and H2 + H2SiSiH2. The silykilylene inserts into SiH4 yielding Si3H8, while disilene is thought to be scavenged successively by two SiH3 radicals, the main reactive species under the given conditions. From the relative rate constants of the three decomposition channels, ΔHf(H3SiSiH:) = 273 ± 11 kJ/mol can be calculated. Also a lower bound to the π bond energy of disilene Bπ(H2SiSiH2) ≥ 69 ± 11 kJ/mol is obtained. Ab initio CI calculations give Bπ(H2SiSiH2) = 93 ± 8 kJ/mol. A substituted disilene is shown to have a probable π bond energy of 108 ± 20 kJ/mol from a thermochemical analysis of literature data.
- Olbrich,Potzinger,Reimann,Walsh
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p. 1267 - 1272
(2008/10/08)
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- Decomposition Kinetics of a Static Direct Current Silane Glow Discharge
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We have studied the decomposition kinetics of a static de silane discharge using mass spectrometric techniques.The principal neutral products observed were hydrogen, disilane, trisilane, trace amounts of higher silanes, and nonstoichiometric silicon hydride solids.The initial rates of formation of the products and depletion of the silane were measured and found to be independent of silane pressure and had a linear dependence on the discharge current.Nitric oxide, a known free-radical scavenger, was introduced into the discharge to determine the relative yields of SiH3 and SiH2.The primary decomposition was found to proceed approximately 80-90percent to the silyl radical, SiH3.The effects of NO addition were the reduction in the formation rate of disilane and trisilane and almost total suppression of solid formation.We propose a mechanism which includes both ion and neutral radical reactions and conclude that the major decomposition processes lead to SiH3 and SiH2.Kinetic treatment of the mechanism gave values for the product yields that were in good agreement with the observed yields.
- Longeway, P.A.,Estes, R.D.,Weakliem, H.A.
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- The 147-nm Photolysis of Disilane
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The photodecomposition of Si2H6 at 147 nm results in the formation of H2, SiH4, Si3H8, Si4H10, Si5H12, and a solid film of amorphous silicon hydride (a-Si:H).Three primary processes are proposed to accoount for the results, namely, (a) Si2H6 + hν -> SiH2 + SiH3 + H (φa=0.61); (b) Si2H6 + hν -> SiH3SiH + 2H (φb=0.18); (c) Si2H6 + hν -> Si2H5 + H (φc=0.21).The overall quantum yields depend on the pressure but at 1 Torr partial pressure of Si2H6 are Φ(-Si2H6)=4.3+/-0.2, Φ(SiH4)=1.2+/-0.4, Φ(Si3H8)=0.91+/-0.08, Φ(Si4H10)=0.62+/-0.03, Φ(Si,wall)=2.2.Quantum yields for H2 formation were not measured.A mechanism is proposed which is shown to be in accord with the experimental facts.
- Perkins, G. G. A.,Lampe, F. W.
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p. 3764 - 3769
(2007/10/02)
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