Substituent effects in cation/pi interactions and electrostatic potentials above the centers of substituted benzenes are due primarily to through-space effects of the substituents.
Substituent effects in cation/pi interactions have been examined using the M05-2X DFT functional and CCSD(T) paired with triple-zeta-quality basis sets. In contrast to popular, intuitive models, trends in substituent effects are explained primarily in terms of direct through-space interactions with the substituents. While there is some scatter in the data, which is attributed to pi polarization, the trend in substituent effects in cation/pi interactions is captured by an additive model in which the substituent is isolated from the aryl ring. Similarly, changes in the electrostatic potential at a point above the center of a substituted benzene arise largely from through-space effects of the substituents; pi polarization is not the dominant underlying cause.
Wheeler
Steven E
SE
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA. swheele2@chem.ucla.edu
Houk
K N
KN
D001555:Benzene Derivatives / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D003198:Computer Simulation; D008956:Models, Chemical; D055672:Static Electricity
D001555:Benzene Derivatives; D002412:Cations