Behaviour of the XH-*-π and YX-*-π interactions (X, Y = F, Cl, Br and I) in the coronene π-system, as elucidated by QTAIM dual functional analysis with QC calculations

Dynamic and Static Nature of XH-∗-π and YX-∗-π (X = F, Cl, Br, and I; Y = X and F) in the Distorted π-System of Corannulene Elucidated with QTAIM Dual Functional Analysis

The dynamic and static nature of the XH-∗-π and YX-∗-π (X = F, Cl, Br, and I; Y = X and F) interactions in the distorted π-system of corannulene (π(C₂₀H₁₀)) is elucidated with a QTAIM dual functional analysis (QTAIM-DFA), where asterisks emphasize the presence of bond critical points (BCPs) on the interactions. The static and dynamic nature originates from the data of the fully optimized and perturbed structures, respectively, in QTAIM-DFA. On the convex side, H in F-H-∗-π(C₂₀H₁₀) and each X in Y-X-∗-π(C₂₀H₁₀) join to C of the central five-membered ring in π(C₂₀H₁₀) through a bond path (BP), while each H in X-H-∗-π(C₂₀H₁₀) does so to the midpoint of C=C in the central five-membered ring for X = Cl, Br, or I. On the concave side, each X in F-X-∗-π(C₂₀H₁₀) also joins to C of the central five-membered ring with a BP for X = H, Cl, Br, and I; however, the interactions in other adducts are more complex than those on the convex side. Both H and X in X-H-∗-π(C₂₀H₁₀) (X = Cl and Br) and both Fs in F-F-∗-π(C₂₀H₁₀) connect to the three C atoms in each central five-membered ring (with three BPs). Two, three, and five BPs were detected for the Cl-Cl, I-H, Br-Br, and I-I adducts, where some BPs do not stay on the central five-membered ring in π(C₂₀H₁₀). The interactions are predicted to have a vdW to CT-MC nature. The interactions on the concave side seem weaker than those on the convex side for X-H-∗-π(C₂₀H₁₀), whereas the inverse trend is observed for Y-X-∗-π(C₂₀H₁₀) as a whole. The nature of the interactions in the π(C₂₀H₁₀) adducts of the convex and concave sides is examined in more detail, employing the adducts with X-H and F-X placed on their molecular axis together with the π(C₂₄H₁₂) and π(C₆H₆) adducts.

Nature of intramolecular O-H⋯π interactions as elucidated by QTAIM dual functional analysis with QC calculations

The intrinsic dynamic and static nature of intramolecular OH-*-π interactions is elucidated using a QTAIM dual functional analysis (QTAIM-DFA) after clarifying the structural features. Asterisks (*) are employed to emphasize the presence of bond critical points (BCPs) on the bond paths (BPs), which correspond to the interactions in question. Data from the fully optimized structures correspond to the static nature of the interactions. In our treatment, data from the perturbed structures, which are based around the fully optimized structure, are employed for the analysis in addition to those from the fully optimized structure, which represent the dynamic nature of the interaction. Seven intramolecular OH-*-C(π) interactions were detected in six-membered rings, with six BPs and BCPs for each, among the 72 conformers of the species examined here (1-15). The interactions are predicted to have a vdW or t-HBnc (typical hydrogen bonds with no covalency) nature, which appeared in the pure closed shell region. They appear to be stronger than the corresponding intermolecular interactions. Nine BPs with BCPs were also detected for the intramolecular O-*-X interactions (X = C(π) and H(π), joined to C(π)) in the 5-7-membered rings. The E(2) values of the interactions, as obtained by NBO, are discussed in relation to the stabilities of the conformers and the BPs with BCPs.