ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Comparison of Theoretical Criteria for the Participation of Tunneling Mechanism in Chemical Reactions

P. Zámečník, P. Šimon, and L. Valko

Department of Physical Chemistry, Faculty of Chemical Technology, Slovak Technical University, CS-812 37 Bratislava

Abstract: Comparison of some theoretical criteria of tunneling effect participation in chemical reactions has been carried out. The predictions of characteristic temperatures and tunneling factors are confronted with the experimental data of intermolecular and intramolecular H atom transfer reactions. The calculations have been performed for two different models of tunneling. The results show strong dependence of the theoretical criteria on the accuracy of the estimation of potential barrier dimensions which lowers the reliability of the predictions. The best agreement between the criteria and experimental data has been reached for vibrational-adiabatic barriers. For exo- and endothermic reactions in condensed phase, the criteria obtained in the framework of the tunneling bonding particle model have appeared to be the most convenient. The criteria based on the model of the tunneling free particle are suitable for reactions in gaseous phase and, in special cases, for athermic reactions in condensed phase.

Full paper in Portable Document Format: 463a145.pdf

Chemical Papers 46 (3) 145–150 (1992)