IR spectroscopy and quantum-mechanical studies on 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 CdC and the CsF stretching vibrations. According to the achieved results it has been inferred that the adsorption can occur through the F atom or the double CdC 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.