Na+ binding by benzyl halides: A DFT study

Abstract

The ability of a benzyl halide to bind Na+ is examined computationally using the ω B97X-D functional. The aug-cc-PVTZ basis set was used except X = I for which aug-cc-PVTZ-PP was used instead. Three stable complexes are found in accord with three possible sites for Na+ binding revealed by the electrostatic potential of the benzyl halide. The free energy barriers for the transition to the most stable complex from the other two complexes are small in all cases. In the most stable complex, Na+ binding exhibits simultaneous interactions between the metal ion with both the benzene ring and the halogen atom. The binding energies for the most stable complex are similar across the various benzyl halides with a calculated average value of 31.43 kcal/mol. The average binding energies for the other two complexes are 19.55 kcal/mol and 22.66 kcal/mol. Comparison with Na+ binding by the methyl halides or benzene is made.