The absolute configuration of t-butanesulfinamide has been determined as(-)-(S)using three different chiroptical spectroscopic methods,namely,vibrational circular dichroism(VCD),electronic circular dichroism(ECD),and optical rotatory dispersion(ORD).Furthermore,the predominant conformation of this molecule is determined to have S=O and NH2 groups staggered with respect to the three methyl groups and to have amine hydrogens in gauche orientation with respect to S=O.The quality of predictions obtained for vibrational properties,namely,vibrational absorption and VCD,is found to be satisfactory with the B3LYP functional and 6-31G* basis set.However,this basis set is found to be inadequate for obtaining reliable predictions of electronic properties,namely,electronic absorption and ECD,but a larger aug-cc-pVDZ basis set is found to provide satisfactory prediction of electronic properties.t-Butanesulfinamide serves as an example which invalidates the recommendation of using the 6-31G* basis set for molecules that exhibit the same sign for the long-wavelength ECD band and ORD.This molecule also emphasizes the importance of simultaneous investigation of ECD and ORD,and the use of multiple chiroptical spectroscopic methods,for reliable determination of molecular stereochemistry.
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