Structures of CH3F⋯CH3F and CH3F⋯H2O complexes in a supersonic jet studied by matrix-isolation infrared spectroscopy and density-functional-theory calculation

The CH3F⋯CH3F and CH3F⋯H2O complexes produced by supersonic-jet expansion have been deposited on a cold plate using a standard matrix-isolation technique. By comparing the infrared spectra measured with an FTIR spectrophotometer with the results of DFT calculations, the structure of CH3F⋯CH3F is estimated to be anti-parallel, while that of CH3F⋯H2O has a bent C–F⋯H–O intermolecular hydrogen bonding. The difference in the structure of CH3F dimer from that of CH3I dimer is explained in terms of the dipole–dipole interaction of two methyl halide molecules and the dispersion force of halogen atoms.