Abstract
Rate constants obtained from total line-shape analysis of 11 temperature-dependent gas-phase NMR spectra of (15N)trifluoroacetamide yielded the following kinetic parameters: ΔG⧧298 = 15.1(0.36) kcal mol-1, ΔH⧧ = 13.3(1.3) kcal mol-1, and ΔS⧧ = −5.9(4.5) cal mol-1 K-1. Ab initio calculations performed at the MP2 level using the 6-311++G(d,p) basis set calculated ΔG⧧298 = 15.19 kcal mol-1, ΔH⧧ = 14.35 kcal mol-1, and ΔS⧧ = −2.82 cal mol-1 K-1 in reasonable agreement with experiment. Hartree−Fock calculations using that basis set were also in reasonable agreement with experiment, yielding ΔG⧧298 = 16.03 kcal mol-1, ΔH⧧ = 14.35 kcal mol-1, and ΔS⧧ = −5.62 cal mol-1 K-1. DFT calculations (B3-PW91) using the same basis set gave results that were considerably less accurate.
Published Version
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