The electronic structure of molecules with the B F and B Cl bond in light of the topological analysis of electron localization function: Possibility of multiple bonds?

Topological analysis of electron localisation function (ELF) has been used to study the nature of the B X (X = F, Cl) bonds in 26 molecules. Twelve small molecules with formal B X, B X, and B X bonds and 14 organoboron molecules with the B Cl bond from the Cambridge Structural Database have been studied using CCSD, DFT(M062x) methods. As the V(B,F) basin population for the investigated molecules is smaller than 4 and 6e, the existence of B X, B X bonds is not confirmed. The results show higher polarity of B F bonds as compared to the B Cl bonds. Electronic structure of selected molecules has been discussed from the ELF-topological perspective.