In contrast, the weak Lewis base N2 forms only weakly bonded adducts with B-N bond lengths of 2.9-3.4 Å and E values of -1.7 to -2.1 kcal mol -1 . Note that, in these cases, the Lewis acid is barely deformed from its planar geometry, and the stability of the final adduct varies little as BX3 is varied from BF3 to BI3. Lastly, the moderate Lewis base MeCN displays bond-stretch isomerism, forming both strongly and weakly bonded adducts with boron trihalides, except in the case of BF3, where only the long-bond adduct is formed. in nature. However, note that, for example, the Cl3BNH3 adduct, which is classified as a donor-acceptor complex, has a larger electrostatic than orbital interaction contribution (Velstat = -118.4 kcal mol⁻¹ and Eoi = -112.2 kcal mol⁻¹, respectively). Similar inconsistencies can be found in Table . This illustrates how the classification by nature is not only limited to a few cases but also misleading, as it overlooks the fact that all complexes exhibit a covalent, that is, HOMO-LUMO molecular orbital interactions (or electrostatic or dispersion) character regardless of their stability (see (Eoi in Table and Figure ). Additionally, it is important to note that dispersion interactions (Edisp) are consistently weak, regardless of whether the complex is classified as van der Waals or donor-acceptor complexes in nature. The relative significance of Edisp only becomes pronounced when the other stabilizing interactionselectrostatic and orbital contributions-are weakened due to the long-range separation of the interacting pair. This effect is exemplified by the Cl3B-NCMe adduct, where the dispersion interaction remains small, yet its relative importance increases compared to donor-acceptor interactions (Table ). Notably, when comparing Cl3BNCMe and Cl3B•••NCMe, Eoi varies by more than 50-fold, whereas Edisp changes by only a factor of two. This highlights the secondary role of dispersion forces in determining the nature of these interactions, reinforcing the need for a more nuanced classification scheme.