Abstract
A systematic benchmark of phosphorus and fluorine NMR chemical shifts
predictions at six different density functional theory (DFT) / the
gauge-including atomic orbital (GIAO) methods was conducted. Two
databases were compiled: one consists of 35 phosphorus-containing
molecules, which cover the most common intra-molecular bonding
environments of trivalent and pentavalent phosphorus atoms; the other is
composed of 46 fluorine-containing molecules. The characteristics of
each DFT/GIAO method with different solvent models were demonstrated in
details. The application of linear regression between the calculated
isotropic shielding constants and experimental chemical shifts was
applicable to improve the prediction accuracy. And, the best methods
with the SMD and CPCM implicit solvent models for 31P
chemical shifts predictions, are able to yield a root-mean-square
deviation (RMSDs) of 5.58 ppm and 5.42 ppm, respectively; for
19F, the corresponding lowest prediction errors with
these two applied solvent models are 4.43 ppm and 4.12 ppm. The
developed scaling factors fitted from linear regression are applicable
to enhance the chance of successful structural elucidations of
phosphorus or fluorine-containing compounds, as an efficient complement
to 13C, 1H, 11B
and 15N chemical shifts predictions.