Inductive and resonance effects based on core-electron binding energy shift

Abstract

It was shown that core-electron binding energy shift (ACEBE) could be used as a criterion of inductive (and resonant) effect at each ring carbon atom of substituted cyclohexanes (and benzenes). CEBEs were calculated using density-functional theory with the scheme ΔEKS (PW86-PW91)/TZP//HF/6-31G*. The inductive effect thus calculated correlate highly with the Taft inductive effect (σ1). The inductive effect in a substituted benzene can be well approximated by that determined in a substituted cyclohexane. Resonant effect was defined as the difference between ΔCEBE of a substituted benzene and ΔCEBE of a substituted cyclohexane. The resonance effect thus defined at para atom in substituted benzenes correlates fairly well with Taft (experimental) resonance effect (σR), very highly with Taft (theoretical) resonance effect (σR, theory) of literature. © 2008 Wiley Periodicals, Inc.