Carbon‐13 n.m.r. and CNDO/S study of 1,3‐indandione and heterocyclic analogues

Abstract
13C n.m.r. spectra are reported for 1,3‐indandione, phthalic anhydride, thiophthalic anhydride, and phthalimide in chloroform‐d solution. The 13C chemical shifts have also been calculated by means of Pople's perturbation theory using CNDO/S wave functions; the agreement between theoretical and experimental values is improved when an empirical charge‐dependent term is added to the calculated diamagnetic and paramagneitc contributions.