Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Physical Chemistry

The present thesis addresses the interactions of v-holecontaining molecules with electron-rich and electron-deficient aromatic s-systems, namely, benzene (BZN), 1,3,5-trifluorobenzene (TFB) and hexafluorobenzene (HFB). The interactions of X₃-C-H, F₃-C-X and F-T-F3(where X= F, Cl, Br and I, and T = C, Si, Ge, and Sn) with BZN, TFB and HFB were investigated. In these interactions, X₃-C-H, F₃-C-X and F-T-F₃ played the role of hydrogen, halogen and tetrel bond donors, respectively, while the electron-rich BZN and the electron-deficient TFB and HFB were the hydrogen, halogen and tetrel bond acceptors. The monomers were optimized at MP2/aug-cc-pVDZ level of ab initiotheory and the molecular electrostatic potential maps were generated at the same level of theory. The binding energies were computed at the same level of theory via potential energy surface (PES) scan. Unexpectedly, the binding energies of the X₃-C-H{u22EF}s-system complexes were larger (i.e., more negative) as the Vs,max values on the hydrogen atoms were smaller. Noncovalent interaction index (NCI-index) could interpret this binding energy pattern as it revealed the interactions of the X₃ atoms with the s-system. Thus the interaction was strongeras the X atom was more polarizable. The quantum theory of atoms in molecules (QTAIM) failed to identify the mentioned bonding between the X₃ atoms and the confronting carbon atoms in the s-system. The binding energies for the F₃-C-X{u22EF}s-system and F-T-F₃{u₂₂EF}s-system complexes correlated with the v-hole magnitudes of the X and T atoms, respectively.

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