Density functional theory calculations of O-17 and C-13 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 O-17 and C-13 NMR chemical shifts of the carbon yl group of aromatic acyl chlorides 1a-n. The aryl groups included substitu ted phenyl, furyl, thienyl and naphthyl. The calculated O-17 chemical shift s correlated well with the experimental values and with Hammett-type sigma (+) constants. Therefore, in many cases it is possible to deduce sigma (+) constants of substituted aryl groups via gas-phase calculation of O-17 chem ical shifts of the carbonyl groups. The sigma (+) values obtained in the ga s-phase calculation show the intrinsic property of substituents, so they pr ovide a good reference set for systematic comparison to evaluate the effect of the environment. Furthermore, the concept of n-pi* mixing can be used t o understand the sensitivity of the O and Cl atoms and the insensitivity of the C atom towards substituent effects in aromatic acyl chlorides. Copyrig ht (C) 2001 John Wiley & Sons, Ltd.