title: Internal dynamics in halogen-bonded adducts: a rotational study of chlorotrifluoromethane-formaldehyde.
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.
authors: Department of Chemistry, University of Bologna, Via Selmi 2, 40126 Bologna (Italy), Fax: (+39) 0512099456.
authors: Qian
authors: Q
authors: Gou
authors: Gang
authors: G
authors: Feng
authors: Luca
authors: L
authors: Evangelisti
authors: Montserrat
authors: M
authors: Vallejo-López
authors: Lorenzo
authors: L
authors: Spada
authors: Alberto
authors: A
authors: Lesarri
authors: Emilio J
authors: EJ
authors: Cocinero
authors: Walther
authors: W
authors: Caminati
keywords: aldehydes; freon-13; halogenation; intramolecular motions; molecular complexes; rotational spectroscopy