Theoretical investigation of the nature and strength of simultaneous interactions of pi-pi stacking and halogen bond including NMR, SAPT, AIM and NBO analysis

摘要

Ab initio MP2/aug-cc-pVDZ calculations were performed to investigate mutual effect between pi-pi stacking and halogen bond interactions in X-ben||pyr center dot center dot center dot Cl-F complexes (X = CN, F, Cl, Br, CH3, OH and H where || and center dot center dot center dot denote pi-pi stacking and halogen bonds). The results indicate the cooperativity of pi-pi stacking and halogen bonds in these complexes. This effect was discussed in terms of the energetic, geometrical parameters and charge-transfer properties of the complexes. To explore on the two-bonded spin-spin coupling constant (2X) J(N-F) across N-15 center dot center dot center dot Cl-35-F-19 halogen bond in X-ben||pyr center dot center dot center dot Cl-F complexes, NMR calculations were performed at PBE0/aug-cc-pVDZ levels of theory. To get more insight into the physical nature of the binding energies, Symmetry Adapted Perturbation Theory calculations were carried out. Energy decomposition indicates that the percentage of the electrostatic term in the halogen bonding system constitutes approximately half of the total attractive binding energies, while the percentage of the dispersion term in the pi-pi stacking complexes constitutes approximately half of the attractive binding energies. In addition, atoms in molecules, natural bond orbital and molecular electrostatic potential were also used to probe the pi-pi stacking interactions and halogen bonding strengths.