Gas-phase nuclear magnetic resonance study of internal isomerization in perfluoro-2-azapropene: Comparison of experimental and computed kinetic parameters

Abstract

Rate constants obtained from total line-shape analysis of five temperature-dependent gas-phase NMR spectra of perfluoroazapropene yielded the kinetic barrier to internal isomerization: G‡298 = 66.9 (0.4) kJ mol−1. Five temperature-dependent liquid spectra (5 mol% in CDCl3) yielded G‡298 = 67.4 (0.8) kJ mol−1. Ab initio calculations performed using the compound methods Complete Basis Set (CBS-4M, QB3, APNO), Gaussian (G1-4), and Weizmann (W1U, WBD) gave results consistent with a transition state corresponding to nitrogen inversion. The values that best matched the experimental G‡298 value for each compound method were 63.9 kJ mol−1 (CBS-APNO), 66.1 kJ mol−1 (G2), and 65.6 kJ mol−1 (W1BD).