Chiroptical properties and molecular geometry of substituted succinic anhydrides and imides

Abstract

U.v. and c.d. spectra have been measured for several α-substituted succinic anhydrides and imides. The observed Cotton effect signs corresponding to the two n–π* electronic transitions can be explained with the octant rule. The strong substituent and solvent dependence of the spectra is a result of the equilibrium between two skewed conformers of the five-membered ring. The geometry and relative energies of the conformers were found from the molecular mechanics (MM2) calculations.