### Abstract

The vibrational spectra of gaseous, liquid and solid CH_{3}SiCl_{3} and CD_{3}SiCl_{3} 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 CD_{3}SiCl_{3} 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 -d_{0} and -d_{3} 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 language | English |
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Pages (from-to) | 621-637 |

Number of pages | 17 |

Journal | Spectrochimica Acta Part A: Molecular Spectroscopy |

Volume | 50 |

Issue number | 3 |

DOIs | |

Publication status | Published - 1994 |

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### ASJC Scopus subject areas

- Engineering(all)

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*Spectrochimica Acta Part A: Molecular Spectroscopy*,

*50*(3), 621-637. https://doi.org/10.1016/0584-8539(94)80174-6

**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.

Research output: Contribution to journal › Article

*Spectrochimica Acta Part A: Molecular Spectroscopy*, vol. 50, no. 3, pp. 621-637. https://doi.org/10.1016/0584-8539(94)80174-6

}

TY - JOUR

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

Y1 - 1994

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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U2 - 10.1016/0584-8539(94)80174-6

DO - 10.1016/0584-8539(94)80174-6

M3 - Article

AN - SCOPUS:0042042853

VL - 50

SP - 621

EP - 637

JO - Spectrochimica Acta - Part A Molecular Spectroscopy

JF - Spectrochimica Acta - Part A Molecular Spectroscopy

SN - 0584-8539

IS - 3

ER -