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  • 1
    Electronic Resource
    Electronic Resource
    Conformational Stability, Structural Parameters, Vibrational Frequencies, and Raman and Infrared Intensities of Allylsilane (1998)
    Springer
    Structural chemistry 9 (1998), S. 265-277 
    Details
    ISSN: 1572-9001
    Keywords: Conformational stability ; structural parameters ; infrared and Raman intensities ; allylsilane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The Raman spectra (3500 to 30 cm−1) of allylsilane, CH2CHCH2SiH3, in the liquid with quantitative depolarization ratios and solid states and the infrared spectra (3500 to 30 cm−1) of the gas and solid have been recorded. Similar data have also been recorded for the Si-d3 isotopomer. Additionally, the mid-infrared spectra of the normal sample dissolved in liquified xenon as a function of temperature (−100 to −50°C) have been recorded. All these data indicate there is a single conformer, the gauche rotamer, in all three physical states. Utilizing the Si-H stretching frequencies from the infrared spectrum of the gaseous CH2CHCH2SiD2H isotopomer, the three Si-H bond distances (r 0) are calculated to be 1.484 Å for the gauche conformer. The other r 0 parameters are estimated from the previously reported rotational constants. The fundamental frequencies for the asymmetric (78 cm−1) and SiH3 (137 cm−1) torsions were obtained from sum and difference bands with the SiH3 stretches. From the SiH3 torsional frequency the barrier to internal rotation is calculated to have a value of 731 cm−1 (8.74 kJ/mol). The optimized geometries, conformational stabilities, harmonic force fields, infrared intensities, Raman activities, depolarization ratios, and vibrational frequencies have been obtained from RHF/6-31G* and/or MP2/6-31G* ab initio calculations. These quantities are compared to the corresponding experimental quantities when appropriate as well as with some corresponding results for some similar molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022478913441
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  • 2
    Electronic Resource
    Electronic Resource
    Spectra and Structures of Silicon-Containing Compounds. XXIV.* Raman and Infrared Spectra, r 0 Structural Parameters, Vibrational Assignment, Barriers to Internal Rotation, and Ab Initio Calculations of Ethylsilane (1998)
    Springer
    Structural chemistry 9 (1998), S. 255-264 
    Details
    ISSN: 1572-9001
    Keywords: Structural parameters ; internal rotational barriers ; ab initio calculations ; ethylsilane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The infrared (3200 to 400 cm−1) and Raman (3200 to 20 cm−1) spectra of gaseous and solid ethylsilane, CH3CH2SiH3, have been recorded. Additionally, the Raman spectrum of the liquid has been obtained with quantitative depolarization values. The SiH3 torsional mode has been observed as sum and difference bands with the silicon-hydrogen stretching vibration. Utilizing the torsional fundamental frequency of 132 cm−1 the threefold periodic barrier of 590 cm−1 (7.06 kJ/mol) has been obtained. Utilizing the frequencies of the silicon-hydrogen stretches, Si-H bond distances of 1.485 and 1.484 Å have been obtained for the bonds gauche and trans to the methyl group, respectively. Using previously reported rotational constants from seven different isotopomers, the r 0 parameters have been calculated and are compared to the corresponding r s parameters. A complete vibrational assignment is proposed that is consistent with the predicted frequencies utilizing the force constants from ab initio MP2/6-31G(d) calculations. Both the infrared intensities as well as the Raman activities and depolarization values have been obtained from the ab initio calculations. Complete equilibrium geometries have been determined by ab initio calculations employing the 6-31G(d), 6-311 + G(d,p), and 6-311+G(2d,2p) basis sets at levels of restricted Hartree–Fock (RHF) and/or Moller–Plesset (MP) to second order. The results are discussed and the theoretical values are compared to the experimental values when appropriate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022426829370
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  • 3
    Electronic Resource
    Electronic Resource
    Conformational Stability, Raman and Infrared Spectra, Vibrational Assignment, and Ab Initio Calculations of Allyltrifluorosilane (1999)
    Springer
    Structural chemistry 10 (1999), S. 1-15 
    Details
    ISSN: 1572-9001
    Keywords: Conformational stability ; structural parameters ; infrared and Raman intensities ; allyltrifluorosilane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The Raman spectra (3500 to 30 cm−1) of allyltrifluorosilane, CH2CHCH2SiF3, in the liquid with quantitative depolarization ratios and solid states, and the infrared spectra (3500 to 30 cm−1) of the gas and solid have been recorded. Additionally, the mid-infrared spectra of the sample dissolved in liquified xenon as a function of temperature (−100° to −55°C) have been recorded. All of these data indicate there are two conformers, the more stable gauche rotamer and a very small amount of the cis conformer in the fluid states, but only the gauche form remains in the polycrystalline solid. The variable temperature studies of the infrared spectrum of the xenon solution indicate a relatively large enthalpy difference of 354±30 cm−1 (4.23±0.36 kJ/mol) between the conformers. The fundamental frequencies for the asymmetric (54 cm−1) and SiF3 (48 cm−1) torsions for the gauche conformer were observed in the far infrared spectrum, and from the SiF3 torsional frequency the barrier to internal rotation is calculated to have a value of 525 cm−1 (6.28 kJ/mol). A complete vibrational assignment is presented for the gauche conformer that is consistent with the predicted wavenumbers utilizing the force constants from ab initio MP2/6-31G* calculations. The optimized geometries, conformational stabilities, harmonic force fields, infrared intensities, Raman activities, depolarization ratios, and vibrational wavenumbers have been obtained from RHF/6-31G* and/or MP2/6-31G* ab initio calculations. These quantities are compared to the corresponding experimental quantities when appropriate as well as with corresponding results for some similar molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022061710477
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  • 4
    Electronic Resource
    Electronic Resource
    Spectra and Structure of Silicon-Containing Compounds. XXV. Raman and Infrared Spectra, r 0 Structural Parameters, Vibrational Assignment, and Ab Initio Calculations of Ethyl Chlorosilane-Si-d2 (1999)
    Springer
    Structural chemistry 10 (1999), S. 333-348 
    Details
    ISSN: 1572-9001
    Keywords: Structural parameters ; internal rotational barriers ; ab initio calculations ; ethyl chlorosilane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The infrared (3200 to 400 cm−1) spectra of gaseous and solid and Raman (3200 to 20 cm−1) spectra of liquid and solid ethyl chlorosilane-Si-d2, CH3CH2SiD2Cl, have been recorded. Both the gauche and trans conformers have been identified in the fluid phases, but only the gauche conformer remains in the solid phase. Variable temperature (−105 to −150°C) studies of the infrared spectra of CH3CH2SiH2Cl dissolved in liquid krypton have been carried out. From these data, the enthalpy difference has been determined to be 78±11 cm−1 (0.93±0.13 kJ/mol), with the gauche conformer the more stable form. Utilizing the frequencies of the silicon-hydrogen stretches, from the chlorosilane-Si-d isotopomer, Si—H bond distances of 1.481 and 1.480 Å have been obtained for the gauche conformer and 1.481 Å for the trans conformer. Complete vibrational assignments are proposed for both isotopomers which are consistent with the predicted frequencies utilizing the force constants from ab initio MP2/6-31G(d) calculations. Both the infrared intensities and the Raman activities and depolarization values have been obtained from the ab initio calculations. Complete equilibrium geometries have been determined by ab initio calculations employing the 6-31(d), 6-311++G(d,p), and 6-311+G(2d,2p) basis sets with full electron correlation by the Moller–Plesset (MP) perturbation method to second order. Continuing the previously reported rotational constants from five different isotopomers and the ab initio predicted structural parameters, adjusted r 0 parameters have been calculated, which are compared to the corresponding r s parameters. The results are discussed and the theoretical values are compared to the experimental values when appropriate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022087310109
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  • 5
    Electronic Resource
    Electronic Resource
    Conformational Studies of Methyl Vinyl Silane from Temperature-Dependent FT–IR Spectra of Xenon and Krypton Solutions (2000)
    Springer
    Structural chemistry 11 (2000), S. 229-240 
    Details
    ISSN: 1572-9001
    Keywords: Conformational stability ; variable-temperature FT–IR spectra ; krypton solutions ; methyl vinyl silane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Variable-temperature (−55 to −155°C) studies of the infrared spectra (3500–400 cm−1) of methyl vinyl silane, CH2CHSiH2CH3, dissolved in liquid xenon and krypton have been recorded. Utilizing three sets of conformer doublets due to the cis and gauche rotamers, the enthalpy difference has been determined to be 133 ± 11 cm−1 (1.59 ± 0.13 kJ/mol) with the gauche conformer the more stable form in the krypton solution. In the xenon solution, the enthalpy difference could not be determined because the infrared bands become so broad and the overlap was so extensive that meaningful areas could not be determined. Ab initio calculations have been carried out with several different basis sets up to MP2/6-311+G(2d,2p) from which structural parameters and conformational stabilities have been determined. With the largest basis set, the cis conformer is predicted to be the more stable conformer, which is inconsistent with the experimental results. Utilizing previously reported microwave rotational constants for both conformers along with the ab initio predicted distances and angles, r 0 parameters have been obtained for both the cis and gauche conformers. The spectroscopic and theoretical results are compared to the corresponding quantities for some similar molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009258109080
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  • 6
    Electronic Resource
    Electronic Resource
    Conformational and Structural Studies of 1-Fluoropropane from Temperature Dependant FT-IR Spectra of Rare Gas Solutions and Ab Initio Calculations (1999)
    Springer
    Structural chemistry 10 (1999), S. 445-461 
    Details
    ISSN: 1572-9001
    Keywords: Conformational stabilities ; FT-IR spectra ; rare gas solutions ; 1-fluoropropane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Variable temperature (−55 to −150°C) studies of the infrared spectra (3500 to 400 cm−1) of 1-fluoropropane, CH3CH2CH2F, dissolved in liquid krypton and xenon have been recorded. Utilizing three conformer pairs in the krypton solution and four conformer pairs in the xenon solution, enthalpy differences of 104±6 cm−1 (1.24±0.07 kJ/mol) and 99±5 cm−1 (1.16±0.06 kJ/mol) were obtained from the krypton and xenon solutions, respectively, with the gauche form the more stable conformer. From these data it is estimated that 24% of the trans forms is present at ambient temperature. The conformational stabilities, harmonic force constants, fundamental frequencies, infrared intensities and Raman activities have been obtained from RHF/6-31G(d) and/or MP2/6-31G(d) ab initio calculations and these quantities have been compared to the experimental values when appropriate. The optimized geometries have also been obtained with several different ab initio basis sets up to MP2/6-311+G(2d,2p). The r0 structural parameters have been obtained by combining the ab initio data with the previously reported rotational constants for both conformers. The results are compared to the corresponding results for some similar molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022483207135
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  • 7
    Electronic Resource
    Electronic Resource
    Spectra and structure of silicon containing compounds (1995)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 352 (1995), S. 499-507 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The Raman (50 to 3200 cm−1) and infrared (50 to 3500 cm−1) spectra of chlorodimethylmethoxysilane, Cl(CH3)2SiOCH3, in the vapor and solid phases have been recorded. Raman spectra of the liquid including depolarization ratios have also been recorded. Optimized geometries and conformational stabilities have been obtained from ab initio calculations utilizing the RHF/3–21G* and RHF/6–31G* basis sets. The calculations from both of these basis sets indicated the gauche conformer to be significantly more stable than the trans conformer. Since the gauche has twice the multiplicity of the trans form it is unlikely that the trans conformer will be detected in the fluid phases at room temperature. This is supported by the fact that no infrared or Raman bands were found to vanish in the spectra of the crystalline solid. The vibrational frequencies have been calculated using appropriate scaling factors, and the vibrational spectra are interpreted in detail. The results have been compared with those obtained for some related molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00323375
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  • 8
    Electronic Resource
    Electronic Resource
    Raman and infrared spectra, vibrational assignment and ab initio calculations of trans-2-methyl-2-butenenitrile (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 26 (1995), S. 933-943 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman (3100-10 cm-1) and infrared (3100-400 cm-1) spectra of trans-2-methyl-2-butenenitrile [trans-CH3CH =C(CH3)CN] were recorded for the gas, liquid and solid phases. Additionally, the far-infrared (370-60 cm-1) spectrum of the gas was recorded. These data were interpreted on the basis that only the trans (two methyl groups trans to each other) isomer is present on purification. Only one of the methyl torsional fundamentals was observed and it corresponds to the methyl group on the same carbon atom as the cyano group. The experimental barrier to internal rotation is 610 ± 30 cm-1 (1.74 ± 0.09 kcal mol-1). The structure, infrared intensities, Raman activities, depolarization ratios and vibrational wavenumbers were determined from ab initio calculations using the RHF/3-21G, RHF/6-31G* and MP2/6-31G* basis sets. These results are compared with those obtained for some related molecules.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250261003
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  • 9
    Electronic Resource
    Electronic Resource
    Raman and infrared spectra, barriers to internal rotation, vibrational assignment and ab initio calculations of 1-bromo-2-methylpropene (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 26 (1995), S. 945-953 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman spectra (3200-20 cm-1) of the liquid and solid phases of 1-bromo-2-methylpropene [BrHC=C(CH3)2] and the infrared (3200-30 cm-1) spectra of the gas and solid were recorded. Additionally, qualitative depolarization values were obtained from the Raman spectrum of the liquid. All of the normal modes were assigned based on band contours, depolarization values, relative intensities and normal coordinate analysis. The torsional transition for the methyl group trans to the bromine atom was observed in the far-infrared spectrum of the vapor at 167 cm-1, and from this wavenumber the barrier to internal rotation was calculated to be 641 cm-1 (1.83 kcal mol-1). Optimized structural parameters, barriers to internal rotation and the wavenumbers for the vibrational fundamentals were calculated using the RHF/STO-3G*, RHF/LANL-1DZ and/or MP2/LANL-1DZ basis sets. All of the results are discussed and compared with the corresponding values obtained for some similar molecules.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250261004
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  • 10
    Electronic Resource
    Electronic Resource
    Raman and infrared spectra, conformational stability, barriers to internal rotation and ab initio calculations of trifluoroacetyl isothiocyanate (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 26 (1995), S. 475-486 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman (3100-10 cm-1) and infrared (3100-30 cm-1) spectra of trifluoroacetyl isothiocyanate [CF3C(O)NCS] were recorded for the gas and solid. Additionally, the Raman spectrum of the liquid was recorded and qualitative depolarization values were obtained. The observed bands are assigned on the basis of the more stable cis conformer (isothiocyanate group cis to the carbonyl bond) and the less stable trans conformer in the vapor state. From the variable-temperature studies of the infrared spectrum of the sample dissolved in liquified xenon, two conformer pairs were used to determine a ΔH value of 104 ± 9 cm-1 (270 ± 26 cal mol-1). From the temperature dependence of the Raman spectrum of the liquid, two conformer pairs were used to determine experimentally a ΔH value of 90 ± 31 cm-1 (258 ± 88 cal mol-1), but for this physical state the trans conformer is the more stable form. In the annealed crystalline solid, only the trans conformer remains. A complete vibrational assignment is proposed for both conformers based on infrared band contours, Raman depolarization data, group wavenumbers and normal coordinate calculations. The experimental conformational stability, barriers to internal rotation and fundamental vibrational wavenumbers are compared with those obtained from the ab initio calculations employing the RHF/6-31G* basis set and to the corresponding quantities obtained for some similar molecules.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250260612
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