Article

Unexpected IR Characteristics of Hydrogen Bonds in the 18-Crown-6-Ether Complex of the H<sub>3</sub>O<sup>+</sup> Hydronium Ion. Can the Location of the Protons Be Specified?

Evgenii S. StoyanovBoreskov Institute of Catalysis, Prospeckt Lavrentieva, 5, Novosibirsk, 60090, Russia, and The Department of Chemistry, University of California, Riverside, California 92521-0403Christopher A. ReedBoreskov Institute of Catalysis, Prospeckt Lavrentieva, 5, Novosibirsk, 60090, Russia, and The Department of Chemistry, University of California, Riverside, California 92521-0403

2004en

ABI

Abstract

The νas(COC) IR spectral signatures of polyethers in H-bonded hydronium ion complexes have been established in studies of H3O+ and H5O2+ complexes with 15-crown-5, 18-crown-6, dibenzo-18-crown-6, and their open chain poly(ethylene glycol) analogues in 1,2-dichoroethane solutions. When experiment meets theory in the structure of the H3O+·18-crown-6 complex, there is disagreement. While DFT calculations at the BLYP/II‘//BLYP/6-31G* level indicate a C3v structure with three normal, static linear H bonds to alternate O atoms of the crown ether, IR spectroscopy in the ν(C−O−C) region indicates that all six O atoms are equivalent. A new type of low-barrier H-bonding involving rotational mobility of H3O+ is proposed to rationalize the experimental observations.

Identifiers

DOI: 10.1021/jp0368177

Citations and references

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