Quantum treatment of hydrogen nuclei in primary kinetic isotope effects in a thermal [1,5]-sigmatropic hydrogen (or deuterium) shift from (Z)-1,3-pentadiene

Yasuaki Itou; Seiji Mori; Taro Udagawa; Masanori Tachikawa; Takayoshi Ishimoto; Umpei Nagashima

doi:10.1021/jp065759x

Quantum treatment of hydrogen nuclei in primary kinetic isotope effects in a thermal [1,5]-sigmatropic hydrogen (or deuterium) shift from (Z)-1,3-pentadiene

J Phys Chem A. 2007 Jan 18;111(2):261-7. doi: 10.1021/jp065759x.

Authors

Yasuaki Itou¹, Seiji Mori, Taro Udagawa, Masanori Tachikawa, Takayoshi Ishimoto, Umpei Nagashima

Affiliation

¹ Faculty of Science, Ibaraki University, Mito 310-8512, Japan.

PMID: 17214462
DOI: 10.1021/jp065759x

Abstract

The geometric and kinetic isotope effects (GIE and KIE) for thermal [1,5]-sigmatropic H and D shifts of (Z)-1,3-pentadiene were studied by including the direct quantum effect of the migrating H or D nucleus in the multi-component molecular orbital-Hartree-Fock (MC_MO-HF) method. Based on the results, the C(1)-D bond lengths are 0.007 Angstrom shorter than the C1-H bond lengths in both the reactant (A) and the transition states (TS), whereas other bond lengths resemble those between H and D. The ratio of the rate constant (k(H)/k(D)) of the reaction for the thermal [1,5]-H and D shifts determined using the MC_MO-HF method (8.28) is closer to the experimental value (12.2) than that determined using either the conventional restricted Hartree-Fock (4.10) or restricted Møller-Plesset second-order perturbation (3.79) methods.