Non covalent interactions stabilizing the chiral dimer of CH 2 ClF: A rotational study

We report the rotational spectra of three isotopologues of the dimer of chlorofluoromethane, namely CH 235 ClF-CH 235 ClF, CH 235 ClF-CH 237 ClF and CH 237 ClF-CH 235 ClF. The assigned (most stable) conformer is chiral (C 1 symmetry) and displays a network of two C-H⋯Cl-C and one C-H⋯F-C weak hydrogen bonds, combined with a Cl⋯F halogen bond. The hyperfine structures due to the quadrupolar effects of the two non-equivalent 35 Cl (or 37 Cl) atoms have been fully resolved, leading to an accurate determination of two sets of diagonal and of some mixed quadrupole coupling constants. Information on the r s positions of the two Cl atoms and on the structural parameters of the hydrogen bonds has been obtained. The dissociation energy of the complex has been estimated as 5.9 kJ mol -1 .