Molecular structure, NMR and vibrational spectral analysis of 2,4-difluorophenol by ab initio HF and density functional theory

Abstract

Quantum chemical calculations of energies, geometries and vibrational wavenumbers of 2,4-difluorophenol (2,4-DFP) were carried out by using ab initio HF and density functional theory (DFT/B3LYP) methods with 6-311G(d,p) as basis set. The optimized geometrical parameters obtained by HF and DFT calculations are in good agreement with related molecules. The best level of theory in order to reproduce the experimental wavenumbers is the B3LYP method with the 6-311G(d,p) basis set. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. A detailed interpretation of the infrared and Raman spectra of 2,4-DFP is also reported. The entropy of the title compound was also performed at HF/6-311G(d,p) and B3LYP/6-311G(d,p) levels of theory. The isotropic chemical shift computed by ¹H, ¹³C NMR analyses also shows good agreement with experimental observations. The theoretical spectrograms for FT-IR and FT-Raman spectra of the title molecule have been constructed. Copyright © 2009 John Wiley & Sons, Ltd.