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Behavior of Halogen Bonds of the Y−X⋅⋅⋅π Type (X, Y=F, Cl, Br, I) in the Benzene π System, Elucidated by Using a Quantum Theory of Atoms in Molecules Dual‐Functional Analysis
Author(s) -
Sugibayashi Yuji,
Hayashi Satoko,
Nakanishi Waro
Publication year - 2016
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201600227
Subject(s) - atoms in molecules , chemistry , halogen , crystallography , hydrogen bond , bent molecular geometry , molecule , halogen bond , electron localization function , benzene , density functional theory , computational chemistry , electron , physics , quantum mechanics , alkyl , organic chemistry
The nature of halogen bonds of the Y−X‐✶‐π(C 6 H 6 ) type (X, Y=F, Cl, Br, and I) have been elucidated by using the quantum theory of atoms in molecules (QTAIM) dual‐functional analysis (QTAIM‐DFA), which we proposed recently. Asterisks (✶) emphasize the presence of bond‐critical points (BCPs) in the interactions in question. Total electron energy densities, H b ( r c ), are plotted versus H b ( r c )− V b ( r c )/2 [=(ħ 2 /8 m )∇ 2 ρ b ( r c )] for the interactions in QTAIM‐DFA, in which V b ( r c ) are potential energy densities at the BCPs. Data for perturbed structures around fully optimized structures were used for the plots, in addition to those of the fully optimized ones. The plots were analyzed by using the polar ( R , θ ) coordinate for the data of fully optimized structures with ( θ p , κ p ) for those that contained the perturbed structures; θ p corresponds to the tangent line of the plot and κ p is the curvature. Whereas ( R , θ ) corresponds to the static nature, ( θ p , κ p ) represents the dynamic nature of the interactions. All interactions in Y−X‐✶‐π(C 6 H 6 ) are classified by pure closed‐shell interactions and characterized to have vdW nature, except for Y−I‐✶‐π(C 6 H 6 ) (Y=F, Cl, Br) and F−Br‐✶‐π(C 6 H 6 ), which have typical hydrogen‐bond nature without covalency. I−I‐✶‐π(C 6 H 6 ) has a borderline nature between the two. Y−F‐✶‐π(C 6 H 6 ) (Y=Br, I) were optimized as bent forms, in which Y‐✶‐π interactions were detected. The Y‐✶‐π interactions in the bent forms are predicted to be substantially weaker than those in the linear F−Y‐✶‐π(C 6 H 6 ) forms.