Kinetics of thermoneutral intermolecular hydrogen migration in alkyl radicals.

High pressure limits of thermal rate constants of intramolecular hydrogen migrations, particularly 1,3 to 1,6 H-shift in propyl, butyl, pentyl and hexyl radicals, respectively, were calculated using the canonical variational transition state theory (CVT) with a multi-dimensional small-curvature tunneling (SCT) correction over the temperature range of 300-3000 K. The CCSD(T)/cc-pVDZ//BH&HLYP/cc-pVDZ method was used to provide necessary potential energy surface information. Rate constants for these reactions were used to extrapolate rate constants for reactions of larger alkyls where experimental data are available using the Reaction Class Transition State Theory (RC-TST). Excellent agreement with experimental data confirms the validity of the RC-TST methodology and the accuracy of the calculated kinetic data in this study.