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Kinetic isotope effects for non‐adiabatic proton transfer in benzophenone— N ‐methylacridan contact radical ion pairs
Author(s) -
Peters Kevin S.,
Kim Ganghyeok
Publication year - 2005
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.849
Subject(s) - chemistry , kinetic isotope effect , deuterium , proton , proton coupled electron transfer , context (archaeology) , adiabatic process , ion , kinetic energy , photochemistry , computational chemistry , electron transfer , thermodynamics , atomic physics , organic chemistry , nuclear physics , biology , quantum mechanics , paleontology , physics
The dynamics of proton transfer within a variety of substituted benzophenones– N ‐methylacridan contact radical ion pairs in benzene were examined. The correlation of the rate constants for proton transfer with the thermodynamic driving force reveals both normal and inverted regions for proton transfer in benzene. Employing the isotopically labeled compounds N ‐methyl‐ d 3 ‐acridan and N ‐methylacridan‐9,9‐ d 2 , the kinetic deuterium isotope effects were examined. The isotope dependence for the transfer process was examined within the context of the Lee–Hynes model for non‐adiabatic proton transfer. The theoretical analysis of the experimental data suggests that the reaction path for proton–deuteron transfer involves tunneling. Conventional transition‐state theory with the inclusion of the Bell correction for tunneling in the region of the transition state cannot account for the observed kinetic behavior. Copyright © 2004 John Wiley & Sons, Ltd.