Density functional theory calculations of 17 O and 13 C NMR chemical shifts for aromatic acyl chlorides

Density functional theory (DFT) at the B3LYP/6–31 + G(d,p)//B3LYP/6–31G(d) level was used to calculate 17 O and 13 C NMR chemical shifts of the carbonyl group of aromatic acyl chlorides 1a – n . The aryl groups included substituted phenyl, furyl, thienyl and naphthyl. The calculated 17 O chemical shifts correlated well with the experimental values and with Hammett‐type σ + constants. Therefore, in many cases it is possible to deduce σ + constants of substituted aryl groups via gas‐phase calculation of 17 O chemical shifts of the carbonyl groups. The σ + values obtained in the gas‐phase calculation show the intrinsic property of substituents, so they provide a good reference set for systematic comparison to evaluate the effect of the environment. Furthermore, the concept of n–π* mixing can be used to understand the sensitivity of the O and Cl atoms and the insensitivity of the C atom towards substituent effects in aromatic acyl chlorides. Copyright © 2001 John Wiley & Sons, Ltd.