title: 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.
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.
authors.affiliation: Faculty of Science, Ibaraki University, Mito 310-8512, Japan.
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Itou
authors.forename: Seiji
authors.initials: S
authors.lastname: Mori
authors.forename: Taro
authors.initials: T
authors.lastname: Udagawa
authors.forename: Masanori
authors.initials: M
authors.lastname: Tachikawa
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ishimoto
authors.forename: Umpei
authors.initials: U
authors.lastname: Nagashima