IR spectroscopy and quantum-mechanical studies of the adsorption of CH2CClF on TiO2

The adsorption at room temperature of 1-chloro-1-fluoroethene (CH2CClF) on TiO2 has been studied by Fourier transform infrared spectroscopy. Vibrational spectra of the adsorbed compound have been compared with those referring to the gas-phase and the most interesting differences consist of a blue -shift of the two C-H stretching modes and the presence of two very distinct absorptions for both the C = C and the C-F stretching vibrations. According to the achieved results it has been inferred that the adsorption can occur through the F atom or the double C = C bond. Unlike the vinyl halides, no formation of an H-bond between the CH2 group and a surface Lewis basic site has been observed. Two proposed acid-base interactions have been studied by quantum-mechanical calculations at the DFT/B3LYP level considering the rutile (110) surface. The interaction energy associated with the two adsorbate-substrate structures is similar and that referred to the adsorption through the F atom is slightly bigger. The shifts obtained in the calculated vibrational frequencies have been found to be in good agreement with the experimental data.