Accuracy vs time dilemma on the prediction of NMR chemical shifts: a case study (chloropyrimidines).
The nuclear magnetic shieldings of two chloropyrimidine species have been predicted and analyzed by means of ab initio and DFT methods. The results have been compared with the experimental values and with those from other database-related approaches. These dataset-based techniques are found to be particularly valuable because of the accurate and instantaneous prediction of the 13C chemical shifts. On the other hand, only a few quantum chemistry based approaches were showed to be the most precise to predict 1H chemical shifts and to elucidate unequivocally the 1H NMR spectra of the regioisomeric mixture under study. Special emphasis was put on incorporating the solvent effect, implicitly, or explicitly. The influence of the level of theory and basis set in the predicted values has also been discussed.
Pérez
Manuel
M
Pfizer Ltd., Global Research and Development, Sandwich Laboratories, Sandwich, Kent, CT13 9NJ, United Kingdom.
Peakman
Torren M
TM
Alex
Alexander
A
Higginson
Paul D
PD
Mitchell
John C
JC
Snowden
Martin J
MJ
Morao
Iñaki
I
D002713:Chlorine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D011744:Pyrimidinones / Q000737:chemistry*; D013997:Time Factors
D011744:Pyrimidinones; D002713:Chlorine