Optical resolution of racemic diaryl selenonium-N-toluene-4'-sulfonimides (
rac-1a-d) by liquid chromatography using an optically active column yielded
optically pure selenonium imides. The absolute configuration around the se
lenium atom of (-)-2,4,6-tri-tert-butyldiphenylselenon N-toluene-4'-sulfoni
mide [(-)-1a] was determined to be S by X-ray crystallographic analysis, an
d those of the other optically active selenonium imides were determined on
the basis of their specific rotations and CD spectra. The kinetics of racem
ization by pyramidal inversion of the optically active selenonium imides ()- and (-)-1b and 1d were studied. The results indicated that the activatio
n energy for the racemization of optically active selenoniun. imides was gr
eater than those for sulfonium imides.