4112-23-6Relevant academic research and scientific papers
Improved First Ionization Potential of the Dimethylsilaethylene Molecule Obtained with High-Temperature Photoelectron Spectroscopy
Dyke, J. M.,Josland, G. D.,Lewis, R. A.,Morris, A.
, p. 2913 - 2916 (1982)
The vacuum-ultraviolet photoelectron spectrum of the pyrolysis products of 1,1-dimethyl-1-silacyclobutane (DMSCB) has been recorded.The band associated with the first ionization potential of the 1,1-dimethyl-1-silaethylene (DMSE) molecule has been observed with vertical and adiabatic ionization potentials of 7.98+/-0.01 eV and 7.71+/-0.03 eV, respectively.Analysis of the observed vibrational structure in this band gave ωe = 760+/-30 cm-1 and this is assigned to excitation of the H2C-Si+ to be derived as 745+/-11 kJ mol-1.
Decomposition of 1,1-dimethyl-1-silacyclobutane on a tungsten filament - Evidence of both ring C-C and ring Si-C bond cleavages
Tong,Shi
experimental part, p. 215 - 222 (2010/10/04)
The decomposition of 1,1-dimethyl-1-silacyclobutane (DMSCB) on a heated tungsten filament has been studied using vacuum ultraviolet laser single photon ionization time-of-flight mass spectrometry. It is found that the decomposition of DMSCB on the W filament to form ethene and 1,1-dimethylsilene is a catalytic process. In addition, two other decomposition channels exist to produce methyl radicals via the Si-CH3 bond cleavage and to form propene (or cyclopropane)/dimethylsilylene. It has been demonstrated that both the formation of ethene and that of propene are stepwise processes initiated by the cleavage of a ring C-C bond and a ring Si-C bond, respectively, to form diradical intermediates, followed by the breaking of the remaining central bonds in the diradicals. The formation of ethene via an initial cleavage of a ring C-C bond is dominant over that of propene via an initial cleavage of a ring Si-C bond. When the collision-free condition is voided, secondary reactions in the gas-phase produce various methyl-substituted 1,3-disilacyclobutane molecules. The dominant of all is found to be 1,1,3,3-tetramethyl-1,3-disilacyclobutane originated from the dimerization of 1,1-dimethylsilene. Copyright
Stationary and Pulsed Photolysis and Pyrolysis of 1,1-Dimethylsilacyclobutane
Brix, Th.,Arthur, N. L.,Potzinger, P.
, p. 8193 - 8197 (2007/10/02)
A study of the photolysis of 1,1-dimethylsilacyclobutane at 147 - 214 nm shows that of the four primary processes identified the predominant mode of decomposition is to C2H4 and dimethylsilaethene.Evidence from experiments in the presence of SF6 suggests that the dimethylsilaethene is formed initially in a vibrationally excited state: +hν -> Me2SiCH2v + CH2=CH2.Laser pulsed photolysis experiments at 193 nm have been carried out to measure tha absorption spectrum of Me2SiCH2, its absorption cross section, and the rate constant for Me2SCH2 combination: 2Me2SiCH2 -> (Me2SiCH2)2.The values obtained are ? (240 nm, base e) = (1.0 +/- 0.2)E-17 cm2 and k7 = (3.3 +/- 0.8)E-11 cm3 s-1.The kinetics of the pyrolysis of have also been reexamined, yielding the following rate constant expressions: k1/(s-1) = E(15.46 +/- 0.13) exp(-(31043 +/- 218)/T) and k-1/k71/2/(cm3/2s-1/2) = E(-7.0 +/- 0.3) exp(-(7850 +/- 300)/T).From these results, the heat of formation, ?-bond energy, and entropy of Me2SiCH2, have been deduced: ΔHfθ (g, 298 K) = 36 +/- 7 kJ mol-1, B? = 157 +/- 11 kJ mol-1, and Sθ(g, 298 K) = 332 +/- 8 J mol-1 K-1.
INFRARED SPECTROSCOPIC STUDY OF VERY LOW PRESSURE PYROLYSIS PRODUCTS OF CYCLOSILTHIANES AND 3,3-DIMETHYL-3-SILATHIETANE ISOLATED IN ARGON MATRICES. A NEW SOURCE OF 1,1-DIMETHYL-1-SILAETHYLENE (Me2Si=CH2), THIOFORMALDEHYDE (H2C=S) AND DIMETHYLSILANTHIONE (Me2Si=S)
Gusel'Nikov, L.E.,Volkova, V.V.,Avakyan, V.G.,Nametkin, N.S.,Voronkov, M.G.,et. al.
, p. 173 - 188 (2007/10/02)
The products of very low pressure pyrolysis (VLPP) of hexamethylcyclotrisilthiane (I), tetramethylcyclodisilthiane (II) and 3,3-dimethyl-3-silathietane (III) were isolated in Ar matrices and were studied by IR spectroscopy.The only pyrolysis product of I was cyclosilthiane II, a dimer of transient dimethylsilanthione (Me2Si=S) (IV).The starting material was recovered on pyrolysis of II.Thermal decomposition of III involves three intermediate unsaturated compounds: dimethylsilaethylene (Me2Si=CH2) (V) and thioformaldehyde (H2C=S) (VI), both isolated in Ar matrix at 10 K, as well as silanthione IV fixed in the matrix in a form of the cyclic diemr II.The latter was also observed in the study of copyrolysis of 1,1-dimethyl-1-silacyclobutane and thietane, being authentic sources of intermediates V and VI.IR spectra of starting compounds I, II and III isolated in Ar matrices were obtained.The theoretical structure of IV and force constant F(Si=S) were determined by the CNDO/2 method.With regard to CNDO/2 errors, Si=S bond distance and F(Si=S) are equal to 1.993 Angstroem and 4.72 mdyn/Angstroem, respectively.Calculation of normal vibrations resulted in the following values of vibrational frequencies of dimethylsilanthione (cm-1): 884 νs(SiC2) (A1), 735 νas(SiC2) (B2), 626 νs(Si=S) (A1), 200 1).
Arrhenius Parameters for the System (CH3)3Si + D2 (CH3)3SiD + D. The (CH3)3Si-D Bond Dissociation Energy
Ellul, R.,Potzinger, P.,Reimann, B.,Camilleri, P.
, p. 407 - 412 (2007/10/02)
The Arrhenius parameters of the reaction (3) (CH3)3Si + D2 -> (CH3)3SiD + D have been determined relative to the recombination of the trimethylsilyl radicals 2(CH3)3Si -> (CH3)3SiSi(CH3)3 (6) yielding Ea(3) - 1/2Ea(6) = 67 +/- 6 kJ mol-1 and A(3)/A(6)1/2 = 10-7+/-0.5 cm3/2 s-1/2.The rate constant for the back reaction (-3) D + (CH3)3SiD -> D2 + (CH3)3Si has been determined to be k(-3) = (2.0 +/- 0.3) * 10-11 exp(-(1440 +/- 55)/T) cm3 s-1.Assuming a negligible activation energy for the recombination reaction (6) gives H0D((CH3)3Si-D) = 388 +/- 7kJ mol-1 in accordance with the accepted literature value.In the experimental part a pulsed Hg sensitized photolysis-resonance absorption technique is described to obtain rate constants for hydrogen atom-molecule reactions.For testing the apparatus the rate constants k(H + C2H2) = (1.4 +/- 0.3)*10-11 exp(-(1363 +/- 80)T) cm3 s-1 and k(H + C2H4) = (1.2 +/- 0.2)*10-12 cm3 s-1 at room temperature have been determined.
Photolysis of 2,2-Dimethyl-2-silabutane (Ethyltrimethylsilane) at 147 nm
Doyle, Daryl J.,Koob, R. D.
, p. 2278 - 2280 (2007/10/02)
Eight stable products in the neat photolysis at 147 nm of ethyltrimethylsilane (ETMS) along with three additional stable products found in the presence of additives are rationalized in terms of five primary molecular products, eight atomic or free radical intermediates, and (CH3)2SiCH2.In decreasing order of importance these are CH3 , C2H4 , (CH3)2SiCH2 , C2H5 , H2 , (CH3)3Si , H*, CH4 , C2H6 , (CH3)3SiCH2 , (CH3)2SiC2H5 , (CH3)3SiC2H4* , (CH3)2SiH , and (CH3)3SiH .In contrast to the photochemistry of tetramethylsilane, many competing primary processes occur and there is little indication of a dominant reaction.This multiplicity of products creates a system too complex for unambiguous elucidation but illustrates many reactions found commonly in photochemical studies of hydrocarbons.It appears that the structure of the molecule and the availability of secondary hydrogens are more important to the overall reaction mechanism than is the presence of silicon.
VERY LOW PRESSURE PYROLYSIS (VLPP) OF MONOSILACYCLOBUTANES. INFRARED ABSORPTIONS OF 1,1-DIMETHYL-1-SILAETHYLENE, (CH3)2Si=CH2, AND 1,1-DIDEUTERIOMETHYL-1-SILAETHYLENE, (CD3)2Si=CH2 ISOLATED IN ARGON MATRICES
Gusel'Nikov, L. E.,Volkova, V. V.,Avakyan, V. G.,Nametkin, N. S.
, p. 137 - 150 (2007/10/02)
The pyrolysis products of 1,1-dimethyl-1-silacyclobutane (DMSCB) and 1,1,3-trimethyl-1-silacyclobutane (TMSCB), and also of the Si-deuteriomethyl analogs (DMSCB-d6 and TMSCSB-d6) isolated in argon matrices at 10 K have been studied by IR spectroscopy.Pyrolysis of DMSCB and TMSCB gives rise to an identical set of bands: 644, 696, 817, 824, 932, 992, 1001 and 1253 cm-1 which permanently vanish with the increase in temperature.Correspondingly, the bands at 543, 580, 683, 718, 722, 768, 891. 929, 985 and 1012 cm-1 are observed in the spectra of pyrolysis productsof DMSCB-d6 and TMSCB-d6.The appearance of an identical set of bands is attributed to 1,1-dimethyl-1-silaethylene (DMSE) isolated in the argon matrix, but in the case of deuterio analogs, to DMSE-d6.Based on normal coordinate treatment, the above mentioned bands have been preliminary assigned to certain modes of vibrations of DMSE and DMSE-d6.
