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International Journal of Innovation and Applied Studies
ISSN: 2028-9324     CODEN: IJIABO     OCLC Number: 828807274     ZDB-ID: 2703985-7
 
 
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Determination of equilibrium distances of Si-F and Si-Cl, certain thermodynamic values and electron affinities of silanes and silyl radicals using the Hartree-Fock (HF) and density functional theory (DFT) ab initio methods


Volume 5, Issue 3, March 2014, Pages 254–260

 Determination of equilibrium distances of Si-F and Si-Cl, certain thermodynamic values and electron affinities of silanes and silyl radicals using the Hartree-Fock (HF) and density functional theory (DFT) ab initio methods

Mohammed El Idrissi1, Abdellah Zeroual2, and Abdeslam El Hajbi3

1 Laboratory of Physical Chemistry, Department of Chemistry, Faculty of Science, Chouaib Doukkali University BP 20, 24000, El Jadida, Morocco
2 Laboratory of Physical Chemistry, Department of Chemistry, Faculty of Science, Chouaib Doukkali University BP 20, 24000, El Jadida, Morocco
3 Laboratory of Physical Chemistry, Department of Chemistry, Faculty of Science, Chouaib Doukkali University BP 20, 24000, El Jadida, Morocco

Original language: English

Received 20 October 2013

Copyright © 2014 ISSR Journals. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract


The two quantum methods Hartree-Fock HF/6-31G* (d, p) and density functional theory DFT/3-21G* (d, p) were used to calculate the equilibrium of the Si-F and Si-Cl bonds in SiH3X compounds where X may be F- or Cl- ; the atomic electron affinity of chloride (Cl-), fluoride (F-), chlorine (Cl) and fluorine (F); entropy (S), heat capacity (Cv), total energy and reaction enthalpy of fluorosilanes, chlorosilanes and silyl radicals; and bond angles and bond lengths of SiH3F and SiH3Cl. Inter-atomic distances of the Si-F and Si-Cl bonds in SiH3F and SiH3Cl calculated using HR and DFT are in good agreement with the experimental values. The optimal distance of the Si-F bond is shorter than that of the Si-Cl bond in SiH3X. Electron affinities calculated using HF and DFT are not in agreement with those obtained experimentally. The values of entropy (S) increase in parallel with the increase in the number of fluorine atoms in the silanes. The geometric structures of SiH3F and SiH3Cl both belong to the C3v point group. Their bond angles are slightly different. SiH3F has slightly higher energy than SiH3Cl. This might be due to the value of the bond angle in SiH3F, which is 109.18

Author Keywords: Bond angle, electron affinity, enthalpy, entropy, energy of reaction, calorific capacity, state correlation diagramme, SN2 reaction.


How to Cite this Article


Mohammed El Idrissi, Abdellah Zeroual, and Abdeslam El Hajbi, “Determination of equilibrium distances of Si-F and Si-Cl, certain thermodynamic values and electron affinities of silanes and silyl radicals using the Hartree-Fock (HF) and density functional theory (DFT) ab initio methods,” International Journal of Innovation and Applied Studies, vol. 5, no. 3, pp. 254–260, March 2014.