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Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
Preference for an ion-neutral complex-mediated pathway over a five-membered-ring H shift in the isomerization of CH3O
C E Hudson1, D J McAdoo, L L Griffin
1Marine Biomedical Institute, University of Texas Medical Branch, Galveston, TX, USA.
Abstract:
Ab initio theory is used to explore whether the path from CH3OH(+)CH2CH 2 (·) (1) to CH3CH2CH2OH(+·) (5) goes by way of a conventional 1,4-H shift to form ·CH2OH(+)CH2CH3 (2), or via the ion-neutral complex-mediated H transfer [CH3OHCH2=CH2](+·) (3) → [CH3CH 2 (·) CH2OH(+)] (4). Five levels of theory all place the highest energy point in the complex-mediated reaction 3 → 4 slightly below that for the 1,4-H shift 1 → 2, but both routes appear energetically feasible near the threshold for the dissociation of 1 to CH3CH2 + CH2=OH(+). Thus, 1 may take both paths to 5. It is concluded that when both a conventional and a complex-mediated pathway seem plausible in a given system, the latter should be considered to be as likely as the former. Ab initio descriptions of other species involved in the isomerization of 1 to 2 also are presented.
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