Observed and calculated 1H and 13C chemical shifts induced by the in situ oxidation of model sulfides to sulfoxides and sulfones.
A series of model sulfides was oxidized in the NMR sample tube to sulfoxides and sulfones by the stepwise addition of meta-chloroperbenzoic acid in deuterochloroform. Various methods of quantum chemical calculations have been tested to reproduce the observed (1)H and (13)C chemical shifts of the starting sulfides and their oxidation products. It has been shown that the determination of the energy-minimized conformation is a very important condition for obtaining realistic data in the subsequent calculation of the NMR chemical shifts. The correlation between calculated and observed chemical shifts is very good for carbon atoms (even for the 'cheap' DFT B3LYP/6-31G* method) and somewhat less satisfactory for hydrogen atoms. The calculated chemical shifts induced by oxidation (the Delta delta values) agree even better with the experimental values and can also be used to determine the oxidation state of the sulfur atom (-S-, -SO-, -SO(2)-).
Dracínský
Martin
M
Institute of Organic Chemistry and Biochemistry, Academy of Science of the Czech Republic, Flemingovo nám. 2, CZ-166 10 Prague 6, Czech Republic.
Pohl
Radek
R
Slavetínská
Lenka
L
Budesínský
Milos
M
D002247:Carbon Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011522:Protons; D011789:Quantum Theory; D012015:Reference Standards; D013440:Sulfides / Q000032:analysis*; D013450:Sulfones / Q000032:analysis*; D013454:Sulfoxides / Q000032:analysis*
D002247:Carbon Isotopes; D011522:Protons; D013440:Sulfides; D013450:Sulfones; D013454:Sulfoxides