An approach to evaluation of 19F-NMR chemical shifts via basis functions analysis in fluorinated small compounds

An extensive GIAO (gauge-including atomic orbital) calculation has been made within Hartree-Fock (HF), density functional theory (DFT) and second-order Moller-Plesset perturbation theory (MP2), in conjunction with selected basis sets for the prediction of 19F chemical shift values of 26 different F nuclei in small fluorine-containing molecules. The effect of four factors, namely, electron correlation treatment, triple-zeta valence shell, diffuse function and polarization function were assessed using a systematic comparison of the results. Based on types of series, the optimized wave functions were proposed for different molecules. An additional comparison of the principal components of the shift tensor has been used as a supplementary study to confirm the validity of the results. For the series of molecules studied, the diffuse function is the most effective factor used in this applied model and the presence of polarization function is important to minimize the difference between theoretical and experimental values. By including the electron correlation treatment, DFT approach with large basis sets provides the most reliable results. In addition, two 24 factorial designs were considered to assess the reliability of applied scheme for selection the most efficient basis function and the results were discussed in this procedure. (c) 2012 Wiley Periodicals, Inc. Concepts Magn Reson Part A 40A: 192204, 2012.