title: Quantum-mechanical evaluation of π-π versus substituent-π interactions in π stacking: direct evidence for the Wheeler-Houk picture.
abstract: The influence of substituents on π-stacking interactions has previously been explained by two competing hypotheses: a nonlocal effect in which tuning of the π density by the substituent alters the interaction (the Hunter-Sanders picture) or a local effect in which the direct interaction of the added substituent and changed polarity of the phenyl-substituent σ bond alter the interaction (the Wheeler-Houk picture). In this work, we applied the recently developed functional-group partition of symmetry-adapted perturbation theory (F-SAPT) to directly quantify these two effects in situ. The results show that both pictures contribute to the change in interaction energy but that the Wheeler-Houk picture is usually dominant.
authors.affiliation: Center for Computational Molecular Science and Technology, School of Chemistry and Biochemistry, School of Computational Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Parrish
authors.forename: C David
authors.initials: CD
authors.lastname: Sherrill
mesh_terms: D008958:Models, Molecular; D011789:Quantum Theory