Quantum mechanical calculations and spectroscopic analysis of fluorinated vinyl ether molecules

Infrared spectroscopy in connection with quantum mechanical calculations ba sed on density functional theory (DFT) method have been used for the charac terization of fluorinated vinyl ethers. A good correspondence between exper imental and calculated spectra has been found. The peculiar behaviour in terms of frequency and intensity parameters relat ive to the C=C stretching normal mode along a series of related compounds h as been analysed and interpreted in terms of atomic polar tensor (APT) and equilibrium charge and charge fluxes (ECCFs) models. This study indicates t hat the IR intensity of the C=C stretching mode is almost completely due to the flux terms, suggesting that the presence of fluorine atoms make the ch arge along C-C bond very mobile. This approach, based on comparative analysis of experimental and theoretica l data, allows a critical comparison between various chemically related mol ecules and provides information on the various effects of chemical substitu tion on the molecular charge distribution. (C) 1999 Elsevier Science S.A. A ll rights reserved.