Non covalent interactions stabilizing the chiral dimer of CH₂ClF: a rotational study

We report the rotational spectra of three isotopologues of the dimer of chlorofluoromethane, namely CH₂³⁵ClF–CH₂³⁵ClF, CH₂³⁵ClF–CH₂³⁷ClF and CH₂³⁷ClF–CH₂³⁵ClF. The assigned (most stable) conformer is chiral (C₁ 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 ³⁵Cl (or ³⁷Cl) 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.