Structure and non-covalent interactions of 1,3-difluoropropane and its complex with water explored by rotational spectroscopy and quantum chemical calculations.

1,3-difluoropropane and its complex with water were characterized by using Fourier transform microwave spectroscopy with the aid of quantum chemical calculations. Rotational spectra of the monomer were extended to the 13C isotopologues which lead to a precise structural determination of the two observed conformers. For the 1,3-difluoropropane-water complex, the most stable isomer has been observed and assigned in the supersonic jet expansion. In the observed isomer, water acts as a proton donor and a proton acceptor forming one O-H⋯F weak hydrogen bond and two C-H⋯O weak hydrogen bonds, respectively. The measurements on the three 13C, 18O, and deuterated water allowed determination of the skeleton structure and evaluation of the weak hydrogen bond parameters. Quantum theory of atoms in molecules, non-covalent interaction, and symmetry-adapted perturbation theory analyses were performed to reveal the nature of the intermolecular non-covalent interactions.