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Updated: Jan 11, 2026

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
Internal rotation and halogen bonds in CF3I···NH3 and CF3I···N(CH3)3 probed by broadband rotational spectroscopy
Susanna L Stephens1, Nicholas R Walker, Anthony C Legon
1School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK.
Abstract:
The rotational spectra of CF(3)I···NH(3) and CF(3)I···N(CH(3))(3) are measured between 6.7 and 18 GHz using a chirped-pulse Fourier transform microwave spectrometer. Transitions in each spectrum are assigned to A and E species associated with ground and excited internal rotor states respectively. Rotational constants, B(0), centrifugal distortion constants, D(J), D(Jm), D(JKm), nuclear quadrupole coupling constants of the (14)N and (127)I atoms, χ(aa)(N) and χ(aa)(I), are determined for each complex. D(JK) is additionally determined for CF(3)I···NH(3). Results are presented for both (14)N and (15)N-substituted isotopologues. All data are consistent with C(3v) symmetric top structures for both complexes. The nuclear quadrupole coupling constants of iodine are determined to be -2230.030(83) MHz and -2241.61(17) MHz in CF(3)I···(14)NH(3) and CF(3)I···(14)N(CH(3))(3) respectively. The data are interpreted through a model that accounts for the internal dynamics of the complexes in order to determine the length of the halogen bond between the iodine and nitrogen atoms, r(N···I). Values of r(N···I) are thus determined to lie in the ranges 3.054 Å > r(N···I) > 3.034 Å and 2.790 Å > r(N···I) > 2.769 Å for CF(3)I···NH(3) and CF(3)I···N(CH(3))(3) respectively.
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