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Systematic characterization of transition states for radical decompositions
Author(s) -
Grela M. A.,
Colussi A. J.
Publication year - 1987
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550190907
Subject(s) - chemistry , radical , transition state , reaction coordinate , kinetic isotope effect , kinetic energy , ab initio , exponential function , function (biology) , computational chemistry , a priori and a posteriori , simple (philosophy) , potential energy , fission , alkyl , characterization (materials science) , decomposition , activation energy , thermodynamics , chemical physics , atomic physics , deuterium , nanotechnology , organic chemistry , quantum mechanics , mathematical analysis , philosophy , physics , mathematics , materials science , epistemology , evolutionary biology , neutron , biology , catalysis
A one‐parameter analytical potential energy function for β‐bonds in free radicals is described, which accounts quantitatively for their observed stretching frequencies and the position and size of the activation barriers for their fission. It is shown that such a function can be used to characterize a priori the corresponding transition states by assuming that the structural and spectroscopic changes taking place along the minimum energy path track the development of pi bonding rather than following a simple exponential dependence on the reaction coordinate. This procedure, tested by comparing predicted A ‐factors and isotope effects with experimental data for alkyl radicals and ab ‐ initio calculations on C 2 H 5 , fully encodes the basic features of radical decomposition reactions and provides a simple, realistic, and self‐consistent technique for the estimation of their kinetic parameters.