Spectra and structure of silicon-containing compounds. XVII. Vibrational and microwave spectra, molecular structure, barrier to internal rotation and ab initio calculations of methyltrichlorosilane

Mohammad A. Qtaitat, Abu Bakar Mohamad, Tarek A. Mohamed, D. J. Gerson, A. Q. McArver, M. S. Afifi, J. R. Durig

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Abstract

The vibrational spectra of gaseous, liquid and solid CH3SiCl3 and CD3SiCl3 have been recorded from 3500 to 40 cm-1. The fundamental vibrations have been assigned, and the degree of vibrational coupling among the normal modes has been determined. A normal coordinate analysis has been carried out by using the force constants obtained from ab initio calculations with the 3-21G* basis set. The microwave spectrum of CD3SiCl3 has been recorded from 26.5 to 40.0 GHz and the A rotational constants of seven isotopomers in a weighted least-squares procedure are: r(SiC)=1.841±0.005 Å, r(SiC)=2.030±0.001Å {right parenthesis, less than}ClSiC=110.5±0.1°, {right parenthesis, less than}ClSiCl=108.4±0.2°, {right parenthesis, less than}HCSi=109.7±0.1° and {right parenthesis, less than}HCH=109.3±0.1°. The barrier to internal rotation has been estimated from the relative intensity to the torsional satellites in the microwave spectrum to be 2.3 and 2.6 kcal/mol, for the -d0 and -d3 molecules, respectively, and from direct observation of the two-quantum transitions in the Raman effect, to be ∼2.5 kcal/mol for both isotopomers. The structural parameters, barrier to internal rotation, and fundamental vibrational frequencies which have been determined experimentally are compared to those obtained from ab initio calculations employing the RHF/3-21Gu* and/or RHF/6-31G* basis sets. Additionally, structural parameters have been calculated with the 6-31G* basis set with electron correlation at the MP2 level. All of the results are discussed and compared to the corresponding quantities obtained for some similar molecules.

Original languageEnglish
Pages (from-to)621-637
Number of pages17
JournalSpectrochimica Acta Part A: Molecular Spectroscopy
Volume50
Issue number3
DOIs
Publication statusPublished - 1994

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Vibrational spectra
Molecular structure
Microwaves
Electron correlations
Silicon
Molecules
Raman scattering
Satellites
Liquids

ASJC Scopus subject areas

  • Engineering(all)

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Spectra and structure of silicon-containing compounds. XVII. Vibrational and microwave spectra, molecular structure, barrier to internal rotation and ab initio calculations of methyltrichlorosilane. / Qtaitat, Mohammad A.; Mohamad, Abu Bakar; Mohamed, Tarek A.; Gerson, D. J.; McArver, A. Q.; Afifi, M. S.; Durig, J. R.

In: Spectrochimica Acta Part A: Molecular Spectroscopy, Vol. 50, No. 3, 1994, p. 621-637.

Research output: Contribution to journalArticle

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title = "Spectra and structure of silicon-containing compounds. XVII. Vibrational and microwave spectra, molecular structure, barrier to internal rotation and ab initio calculations of methyltrichlorosilane",
abstract = "The vibrational spectra of gaseous, liquid and solid CH3SiCl3 and CD3SiCl3 have been recorded from 3500 to 40 cm-1. The fundamental vibrations have been assigned, and the degree of vibrational coupling among the normal modes has been determined. A normal coordinate analysis has been carried out by using the force constants obtained from ab initio calculations with the 3-21G* basis set. The microwave spectrum of CD3SiCl3 has been recorded from 26.5 to 40.0 GHz and the A rotational constants of seven isotopomers in a weighted least-squares procedure are: r(SiC)=1.841±0.005 {\AA}, r(SiC)=2.030±0.001{\AA} {right parenthesis, less than}ClSiC=110.5±0.1°, {right parenthesis, less than}ClSiCl=108.4±0.2°, {right parenthesis, less than}HCSi=109.7±0.1° and {right parenthesis, less than}HCH=109.3±0.1°. The barrier to internal rotation has been estimated from the relative intensity to the torsional satellites in the microwave spectrum to be 2.3 and 2.6 kcal/mol, for the -d0 and -d3 molecules, respectively, and from direct observation of the two-quantum transitions in the Raman effect, to be ∼2.5 kcal/mol for both isotopomers. The structural parameters, barrier to internal rotation, and fundamental vibrational frequencies which have been determined experimentally are compared to those obtained from ab initio calculations employing the RHF/3-21Gu* and/or RHF/6-31G* basis sets. Additionally, structural parameters have been calculated with the 6-31G* basis set with electron correlation at the MP2 level. All of the results are discussed and compared to the corresponding quantities obtained for some similar molecules.",
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T1 - Spectra and structure of silicon-containing compounds. XVII. Vibrational and microwave spectra, molecular structure, barrier to internal rotation and ab initio calculations of methyltrichlorosilane

AU - Qtaitat, Mohammad A.

AU - Mohamad, Abu Bakar

AU - Mohamed, Tarek A.

AU - Gerson, D. J.

AU - McArver, A. Q.

AU - Afifi, M. S.

AU - Durig, J. R.

PY - 1994

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N2 - The vibrational spectra of gaseous, liquid and solid CH3SiCl3 and CD3SiCl3 have been recorded from 3500 to 40 cm-1. The fundamental vibrations have been assigned, and the degree of vibrational coupling among the normal modes has been determined. A normal coordinate analysis has been carried out by using the force constants obtained from ab initio calculations with the 3-21G* basis set. The microwave spectrum of CD3SiCl3 has been recorded from 26.5 to 40.0 GHz and the A rotational constants of seven isotopomers in a weighted least-squares procedure are: r(SiC)=1.841±0.005 Å, r(SiC)=2.030±0.001Å {right parenthesis, less than}ClSiC=110.5±0.1°, {right parenthesis, less than}ClSiCl=108.4±0.2°, {right parenthesis, less than}HCSi=109.7±0.1° and {right parenthesis, less than}HCH=109.3±0.1°. The barrier to internal rotation has been estimated from the relative intensity to the torsional satellites in the microwave spectrum to be 2.3 and 2.6 kcal/mol, for the -d0 and -d3 molecules, respectively, and from direct observation of the two-quantum transitions in the Raman effect, to be ∼2.5 kcal/mol for both isotopomers. The structural parameters, barrier to internal rotation, and fundamental vibrational frequencies which have been determined experimentally are compared to those obtained from ab initio calculations employing the RHF/3-21Gu* and/or RHF/6-31G* basis sets. Additionally, structural parameters have been calculated with the 6-31G* basis set with electron correlation at the MP2 level. All of the results are discussed and compared to the corresponding quantities obtained for some similar molecules.

AB - The vibrational spectra of gaseous, liquid and solid CH3SiCl3 and CD3SiCl3 have been recorded from 3500 to 40 cm-1. The fundamental vibrations have been assigned, and the degree of vibrational coupling among the normal modes has been determined. A normal coordinate analysis has been carried out by using the force constants obtained from ab initio calculations with the 3-21G* basis set. The microwave spectrum of CD3SiCl3 has been recorded from 26.5 to 40.0 GHz and the A rotational constants of seven isotopomers in a weighted least-squares procedure are: r(SiC)=1.841±0.005 Å, r(SiC)=2.030±0.001Å {right parenthesis, less than}ClSiC=110.5±0.1°, {right parenthesis, less than}ClSiCl=108.4±0.2°, {right parenthesis, less than}HCSi=109.7±0.1° and {right parenthesis, less than}HCH=109.3±0.1°. The barrier to internal rotation has been estimated from the relative intensity to the torsional satellites in the microwave spectrum to be 2.3 and 2.6 kcal/mol, for the -d0 and -d3 molecules, respectively, and from direct observation of the two-quantum transitions in the Raman effect, to be ∼2.5 kcal/mol for both isotopomers. The structural parameters, barrier to internal rotation, and fundamental vibrational frequencies which have been determined experimentally are compared to those obtained from ab initio calculations employing the RHF/3-21Gu* and/or RHF/6-31G* basis sets. Additionally, structural parameters have been calculated with the 6-31G* basis set with electron correlation at the MP2 level. All of the results are discussed and compared to the corresponding quantities obtained for some similar molecules.

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