To conclude, therefore, the interaction between the stacked aromatic groups in Ru16-opt and Ru17-opt has mostly an electrostatic nature, resulting from the interactions between the quadrupole moments of the stacked aromatic rings. The charge alternation in the resulting quadrupolar moments leads to the N-phenyl ring interacting more strongly with the pentafluorophenyl ring in Ru17-opt than with the phenyl ring in Ru16-opt and, as a consequence, to shorter centroid's distances in Ru17-opt (3.607 and 3.612 Å) than in Ru16-opt (3.427 and 3.450 Å). In view of the little NBO energy interaction between the π orbitals of the stacked rings in both Ru16-opt and Ru17-opt, the small π-π orbital overlapping is rather a consequence of the spatial proximity of the stacked aromatic rings, with the slightly stronger π-π orbital overlapping in complex Ru17opt coming from the closer proximity of the N-phenyl ring with the pentafluorophenyl ring in Ru17-opt than with the phenyl ring in Ru16-opt.