DFT INVESTIGATION OF GEOMETRICAL STRUCTURE, IR AND RAMAN SPECTRA OF VINYL HALIDES CH2=CH–X (X IS F, Cl AND Br)Abstract
The geometrical structure and conformational energy stability of vinyl halides CH2=CH–X (X = F, Cl, and Br) were examined by using Density Functional Theory calculations (B3LYP method in combination with 6-311G* basis sets). The values of HOMO-LUMO gap (DE) for vinyl halides (fluoride, chloride and bromide) were 7.68 (eV), 7.10 (eV) and 6.55 (eV) respectively. The calculated geometrical parameters were in good agreement with the previously observed results. Both HOMO-LUMO gap and geometrical parameters were found to account for the stability of the molecules. Electron distribution in HOMO-LUMO Frontier molecular orbitals was investigated to show the charge transfer within the molecules. The atomic charges and molecular electrostatic potential were interpreted together to demonstrate the electrophilic -nucleophilic reactivity. The vibrational frequencies were computed, the comparison between the three halides revealed that vinyl chloride and vinyl bromide have strong C-X stretching vibrations bands, but for vinyl fluoride the bands are weaker, the intensity characterization increasing from F to Br respectively.
T. A. Yousef, R. K. Hussein * and M. Abou-krisha
Department of Physics, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh, KSA.
26 June 2019
03 November 2019
06 November 2019
01 December 2019