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

Abstract

An extensive GIAO (gauge‐including atomic orbital) calculation has been made within Hartree‐Fock (HF), density functional theory (DFT) and second‐order Møller−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‐ξ 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. © 2012 Wiley Periodicals, Inc. Concepts Magn Reson Part A 40A: 192–204, 2012.

Evaluating electronic structure methods for accurate calculation of 19F chemical shifts in fluorinated amino acids

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Spectroscopic, thermal analysis and DFT computational studies of salen-type Schiff base complexes

“…In addition, a comparison was made between the theoretically calculated 13 C chemical shift constants and the experimentally measured 13 C chemical shifts. GIAO (Gauge Including Atomic Orbital) as the most widely used approach for calculating NMR shielding tensors were applied [27][28][29][30][31][32][33]. The Gaussian 09 package was employed to perform optimization of structures and all the calculations [34].…”

Layer selection effect on solid state 13C and 15N chemical shifts calculation using ONIOM approach

“…Based on preliminary experiences [18,19,[50][51][52][53][54][55][56], three factors of electron correlation (A), triple-x valance shell (B), and diffuse function (C) were selected for a high layer of 2-layer ONIOM approach. Each factor was considered at two levels, with ( þ) and ( À ) for high and low level, respectively.…”