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From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
Internal dynamics in halogen-bonded adducts: a rotational study of chlorotrifluoromethane-formaldehyde
Qian Gou1, Gang Feng, Luca Evangelisti
1Department of Chemistry, University of Bologna, Via Selmi 2, 40126 Bologna (Italy), Fax: (+39) 0512099456.
Abstract:
The rotational spectra of two isotopologues of the 1:1 complex between chlorotrifluoromethane and formaldehyde have been recorded and analyzed by using Fourier-transform microwave spectroscopy. Only one rotamer was detected, with the two constituent molecules held together through a Cl⋅⋅⋅O halogen bond (R(Cl⋅⋅⋅O) = 3.048 Å). The dimer displays two simultaneous large-amplitude intramolecular motions. The internal rotation of formaldehyde around its symmetry axis (V2 = 28(5) cm(-1)) splits all the rotational transitions into two component lines with a relative intensity ratio of 1:3. On the other hand, the almost free internal rotation (V3 ≈ 2.5 cm(-1)) of the CF3 symmetric top increases the "rigid" value of the rotational constant A by almost one order of magnitude. In addition, all the transitions display a hyperfine structure due to the (35)Cl (or (37)Cl) nucleus quadrupole effects.
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