Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Hydrates of trans- and gauche-difluoroacetic acids
T2 - A high-resolution microwave spectroscopic study
AU - Ouyang, Bin
AU - Howard, Brian J.
PY - 2010/4/1
Y1 - 2010/4/1
N2 - Although identical in formula, trans- and gauche-difluoroacetic acids behave as different molecules in rotational spectra due to their distinct sets of rotational constants. In this study, high-resolution microwave spectra of monohydrates, dihydrates, and trihydrates of both trans- and gauche-difluoroacetic acids were recorded using a Fourier transform microwave spectrometer. Rotational and centrifugal distortion constants of these hydrates were obtained with high accuracy via fitting their microwave spectra. It was found that the subtle structural difference between the trans and gauche forms of the acid gives different tunneling motions in their monohydrates. An unusual mixing of wave functions of energetically nondegenerate conformations was observed in the monohydrate of gauche-difluoroacetic acid. Ab initio calculations using the second-order Møller-Plesset perturbation method were also performed to optimize structures and to predict magnitudes of dipóle moments of these hydrates. Close agreement between experimental and theoretical rotational constants confirms the feature of hydrogen-bonded ring structures in which all incoming H2O molecules bind to the carboxylic group for all hydrates.
AB - Although identical in formula, trans- and gauche-difluoroacetic acids behave as different molecules in rotational spectra due to their distinct sets of rotational constants. In this study, high-resolution microwave spectra of monohydrates, dihydrates, and trihydrates of both trans- and gauche-difluoroacetic acids were recorded using a Fourier transform microwave spectrometer. Rotational and centrifugal distortion constants of these hydrates were obtained with high accuracy via fitting their microwave spectra. It was found that the subtle structural difference between the trans and gauche forms of the acid gives different tunneling motions in their monohydrates. An unusual mixing of wave functions of energetically nondegenerate conformations was observed in the monohydrate of gauche-difluoroacetic acid. Ab initio calculations using the second-order Møller-Plesset perturbation method were also performed to optimize structures and to predict magnitudes of dipóle moments of these hydrates. Close agreement between experimental and theoretical rotational constants confirms the feature of hydrogen-bonded ring structures in which all incoming H2O molecules bind to the carboxylic group for all hydrates.
U2 - 10.1021/jp9103849
DO - 10.1021/jp9103849
M3 - Journal article
AN - SCOPUS:77950244852
VL - 114
SP - 4109
EP - 4117
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
SN - 1089-5639
IS - 12
ER -