Non-covalent interactions - QTAIM and NBO analysis

MP2(full)/6-311++G(3df,3pd) calculations were carried out on complexes linked through various non-covalent Lewis acid - Lewis base interactions. These are: hydrogen bond, dihydrogen bond, hydride bond and halogen bond. The quantum theory of A ' atoms in moleculesA ' (QTAIM) as well as the natural bond orbitals (NBO) method were applied to analyze properties of these interactions. It was found that for the A-HaEuro broken vertical bar B hydrogen bond as well as for the A-XaEuro broken vertical bar B halogen bond (X designates halogen) the complex formation leads to the increase of s-character in the A-atom hybrid orbital aimed toward the H or X atom. In opposite, for the AaEuro broken vertical bar H-B hydride bond, where the H-atom possesses negative charge, the decrease of s-character in the B-atom orbital is observed. All these changes connected with the redistribution of the electron charge being the effect of the complex formation are in line with BentA ' s rule. The numerous correlations between energetic, geometrical, NBO and QTAIM parameters were also found.