Kinetic Studies of the Reactions of Alkyl and Silyl Hydrides Page: 73
ix, 125 leaves : ill.View a full description of this dissertation.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
73
and error method and a value of 14.6 kJ mol"1 with a root-mean-square deviation of about
15% was obtained. Model (II) applies the Wigner tunneling correction based on the v* =
1880i cm"1 of SiH5' derived from ab initio methods. This frequency calculation was done
using the Gaussian 90 program at the MP2/6-31G* level (which includes the consideration
of electron correlation by perturbation theory).99 In this model, a close fit to the
experimental data was obtained with a standard deviation of 8% using E0* = 18.1 kJ mol"1.
However, the value of E0' from the MP2/6-31G* calculation was in poor agreement (too
high) with the one from the experimental fit, which indicates that the energy change along
the RC of this reaction was poorly described at this theory level.
A higher theory level (G2) of energy calculation was employed by Goumri et al. to
estimate the curvature more accurately, but the frequency calculation was not allowed due
to computer limitations at that time. Owing to the availability of the G2 energies and their
geometries along the course of the reaction (reactants - TS - products), the vibrational
frequency of TS can be calculated on the assumption of a valence force model which was
first proposed by Bjerrum105 in 1914. He assumed that there is a strong restoring force in
the line of every valence bond and which opposed the change of angle between two
valance bonds if the distances of these two bonds are changed. In this case, the geometry
of SiH3 is almost unchanged along the reaction coordinate, RC, so the C3v symmetry of the
transition state can be treated as a linear triatomic molecule SiH3-H-H. Such a system has
two different force constants corresponding to the stretching of the two bonds and one
corresponding to bending of the molecule. The two vibrational frequencies of this
approximated linear triatomic molecule SiH3-H-H can be calculated by the formula
Upcoming Pages
Here’s what’s next.
Search Inside
This dissertation can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Dissertation.
Yuan, Jessie (Jessie Win-Jae). Kinetic Studies of the Reactions of Alkyl and Silyl Hydrides, dissertation, August 1996; Denton, Texas. (https://digital.library.unt.edu/ark:/67531/metadc277864/m1/84/: accessed July 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; .