Behavior of Intramolecular p-p Interactions with Doubly Degenerated Bond Paths Between Carbon Atoms in Opposite Benzene Rings of Diethenodihydronaphthalenes by QTAIM Approach

摘要

Dynamic and static nature of intramolecular π-π interactions between ethylene moieties in diethenodihydronaphthanaphtalene (1b) and derivatives (2b-12b) are elucidated by employing QTAIM-DFA (QTAIM dual functional analysis). During the course of the investigations, doubly degenerated bond paths were detected between carbon atoms in opposite benzene rings of dibenzo-derivative of 1b with an etheno-bridge on the backside (11b). It must be very curious, since one BP should correspond to an interaction between two carbon atoms. Intramolecular p-p interactions in 1b-12b are all classified by the pure CS (closed shell) interactions. The interactions between ethylene groups, with no substituents as in 1b-8b, are predicted to have the van der Waals (vdW) nature. Those for 9b-12b have the hydrogen bond (HB) nature with no covalency, where the ethylene moieties are included in one or two benzene ring(s), except for 10b, if evaluated with MP2/6- 311G(3d). The character in 10b is close to the borderline area between the vdW and HB nature with no covalency, although should be the vdW type. The interactions in 2b-12b evaluated with MP2/6-311G(3d) are predicted to be somewhat stronger than the case with MP2/6-311G(d), as a whole.