Quantum chemical prediction of the ¹³C NMR shifts in alkyl and chlorocorannulenes: Correction of chlorine effects

Abstract

Prediction of the 13C NMR shifts of sym-pentachlorocorannulene and decachlorocorannulene provided impetus for the development of a correction scheme based on a regression of experimental and quantum chemical data. A training set of 15 compounds (18 carbon signals) comprising carbons atoms bearing 1-4 chlorine atoms leads to an estimated error per chlorine atom of about 10-12 ppm. Specifically, linear regression of the data obtained at B3LYP/cc-pVDZ leads to y = -3.77 + 13.11x, with R = 0.982. Ultimately, experiment and theory converge for sym-pentachlorocorannulene and decachlorocorannulene, the former by correction of the theory, the latter by collecting the proper experimental data. © 2007 Springer-Verlag.