Dipole moments and absorption spectra of heterocyclic diketones

Abstract

The electric dipole moments of isatin, benzo[b]furan-2,3-dione, benzo[b]thiophen-2,3-dione, and benzo[c]thiophen-1,3-dione in benzene solution at 25 °C have been measured and compared with those of their congeners related to indane-1,2- and -1,3-dione. The main features of the electronic spectra of all these diketones have been surveyed and interpreted with the aid of theoretical calculations performed at the INDO/S-Cl level; in particular, the nature, location, and evolution of the n→π* transitions have been explained.