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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. April 2002, Volume 1, Number 4, 193-202 |
Quantitative Relationship between Rate Constants of the Gas-Phase Homolysis
of N-N, O-O and N-O Bonds and Molecular Descriptors
Rein Hiob and Mati Karelson
Internet Electron. J. Mol. Des. 2002, 1, 193-202
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Abstract:
Quantitative structure-property relationships (QSPR) for
kinetic parameters of the gas-phase homolysis for N-N, O-O, and N-O
bonds can be used to predict rate constants by using theoretical
descriptors computed from the chemical structure.
QSPR models were obtained using the CODESSA program.
The molecular structures were generated using the PCMODEL
program and the three-dimensional optimization of molecules was
carried out using the semi-empirical MNDO parameterization. The
property characteristics log k (552) were computed according to the
Arrhenius equation using literature values of log A and E at T = 552 K.
Good individual five-parameter correlations were obtained
for the log k (552) of compounds involving N-N and N-O, and three-parameter
correlation for O-O bond fission, respectively. The
corresponding correlation coefficients squared R2 were spanning from
0.9774 to 0.9969 and the standard deviations s from 0.19 to 0.47.
The application of the CODESSA approach allows
confident prediction of the kinetic parameters log k (552) of the gas-phase
homolysis of three different types of the homolyzing bonds
using the molecular descriptors derived from the structure.
Statistically good correlations are obtained for N-N, O-O and N-O
bonds with uncertainties in the predictions comparable to the
uncertainties in the values for the experimental estimates.
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