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Ab initio study of the topology of the charge distribution of H3SiO(H)AlH3 conformers

✍ Scribed by Humberto Soscun; Javier Hernández; Olga Castellano

Publisher
John Wiley and Sons
Year
2000
Tongue
English
Weight
950 KB
Volume
76
Category
Article
ISSN
0020-7608

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✦ Synopsis

The topologic properties of the electronic charge distribution of Ž . conformers of H SiO H AlH molecule hydroxyl groups of zeolites are reported. The 3 3 studied properties-total density, Laplacian density, and bond ellipticity-were evaluated at the position of the critical points of the O᎐Si, O᎐Al, and O᎐H bonds, by using Hartree᎐Fock and second-order Møller᎐Plesset levels of theory, and the STOr6-31 Ž .

Ž . q G d,p standard basis set. For the H SiO H AlH molecule, four conformers are 3 3 identified. It is demonstrated that for these conformers, the total density and Laplacian Ž . density remain almost constant by effect of the rotations of the T᎐H bonds, T s Si, Al , around the corresponding O᎐T bonds, respectively. However, these rotations induce sensible variations in the ellipticity at the position of the critical point of the O᎐Al bonds, which are reflected in the OH bond distance, OH vibrational mode, and the stabilization energy of conformers. These results lead to a linear relationship between the magnitude of the bond ellipticity at the critical point of the O᎐Al bonds and the frequency values of the OH bonds, with a correlation coefficient of r 2 s 0.98. In addition, a good linear relationship between the ellipticity of the O᎐Al bond and the pattern of the stabilization energy of conformers was also found.

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