Origin of Attraction and Directionality of the π/π Interaction:  Model Chemistry Calculations of Benzene Dimer Interaction

Abstract

A model chemistry for the evaluation of intermolecular interaction between aromatic molecules (AIMI Model) has been developed. The CCSD(T) interaction energy at the basis set limit has been estimated from the MP2 interaction energy near the basis set limit and the CCSD(T) correction term obtained by using a medium size basis set. The calculated interaction energies of the parallel, T-shaped,and slipped-parallel benzene dimers are -1.48, -2.46, and -2.48 kcal/mol, respectively. The substantial attractive interaction in benzene dimer, even where the molecules are well separated, shows that the major source of attraction is not short-range interactions such as charge-transfer but long-range interactions such as electrostatic and dispersion. The inclusion of electron correlation increases attraction significantly. The dispersion interaction is found to be the major source of attraction in the benzene dimer. The orientation dependence of the dimer interaction is mainly controlled by long-range interactions. Although electrostatic interaction is considerably weaker than dispersion interaction, it is highly orientation dependent. Dispersion and electrostatic interactions are both important for the directionality of the benzene dimer interaction.

Cationic half-sandwich complexes (Rh,Ir,Ru) containing 2-substituted-1,8-naphthyridine chelating ligands: Syntheses, X-ray structure analyses and spectroscopic studies

“…6). The distance observed between the two p-stacking interacting systems (centroidÁÁÁcentroid 3.62 Å) is in good agreement with the theoretical value calculated for a slipped parallel stacking mode [19].…”

Encapsulation of Triphenylene Derivatives in the Hexanuclear Arene Ruthenium Metallo‐Prismatic Cage [Ru6(p‐PriC6H4Me)6(tpt)2(dhbq)3]6+ (tpt = 2,4,6‐tri(pyridin‐4‐yl)‐1,3,5‐triazine, dhbq = 2,5‐dihydroxy‐1,4‐benzoquinonato)

“…It is clear from the van der Waals representation of the carceplex system that the hexamethoxytriphenylene is permanently encapsulated in 1, see Figure 4. The interplanar separation observed between the central aromatic moieties (3.29 Å ), is shorter than the theoretical value calculated for this stacking mode [14], confirming strong π-stacking interaction between the triazine rings and the central aromatic ring of the triphenylene moiety. The empty spaces left between the cationic hexanuclear cages are filled with [O 3 SCF 3 ] Ϫ anions and benzene solvent molecules.…”

The Adaptable Coordination Chemistry of 6‐Chloro‐2‐(quinolin‐2‐yl)‐2,4‐dihydro‐1H‐benzo[d][1,3]oxazine Towards Zinc(II) and Mercury(II)

“…The distance observed between the π-π interacting systems is in accordance with the theoretical value calculated for this stacking mode. [21] Moreover, the N-H function of LH 2 forms a strong hydrogen bond with a neighbouring oxygen atom: The N···O distance is 3.00(1) Å with an N-H···O angle of 167.9°. These interactions are summarized in Figure 4.…”