Interplay between dihydrogen and alkali–halogen bonds: Is there some covalency upon complexation of ternary systems?

In this study, a theoretical investigation of traditional dihydrogen bonds and novel alkali–halogen bonds was performed in relation to the formation of NaH⋯HCF3 and NaH⋯HCCl3 binary and NaH⋯2(HCF3) and NaH⋯2(HCCl3) ternary complexes. The B3LYP/6-311++G(3df,3pd) level of theory was used to determine the optimized geometries of these complexes, mainly in order to examine the most important structural deformations. In addition to the infrared harmonic spectrum from which the red- and blue-shift effects were interpreted following NBO analysis, intermolecular energies (BSSE and ZPE included), dipole moment variations, quantification of charge transfer through the CHELPG and Mulliken approaches, and the Bader topology were considered in the modeling of the intermolecular covalence through the measurement of the kinetic and potential electronic energy densities.