Theoretical Study on Interaction of Fluorine-Containing Compounds Involving the Fourth Period Metal Elements With N-base: Comparison With Halogen Bonds

Abstract

The fourth period metal fluorides acting as a Lewis acid form binary compounds with nitrogen-containing bases (HCN, NHCH₂, and NH₃), which the calculations are carried out at the MP2 ab initio level with the AVTZ and AVQZ basis set and employed by the CBS method. AIM and IGMH analyses further indicate that the metal-N-bases (M─N) bonding exists in the binary complexes. The strength of interactions is ranging from −4.76 to −56.54 kcal/mol. M─N bonding exhibits a partially covalent nature characterized with a negative energy density and large interaction energy. With the decrease of electronegativity of the substituents on the Lewis base, the interaction energies increase. The M─N interaction is dominated by electrostatic interaction in all complexes, whereas induction and dispersion energies cannot be ignored either.