Dipole moments and electronic structure of some xanthine and thioxanthine derivatives

Abstract

The dipole moments and u.v. absorption spectra of caffeine, theophylline, and thier 2-thio-, 6-thio- and 2,6-dithio-derivatives have been measured. From the differences between the moments of these compounds it can be deduced that the group moment of CS is by 1·1 D higher than that of CO; the direction of the moment of caffeine forms an angle of 96° counterclockwise with the C(4)→ C(5) axis, in good agreement with theoretical predictions.