Theoretical insights and quantitative prediction of the nature of boron-chalcogen (O, S, Se, Te) interactions using the electron density and the electron localisation function (ELF)

Local electronic structure of the boron-chalcogen bond B-Ch (Ch = O, S, Se, Te) has been investigated from the perspective of topological analysis of the electron localisation function (ELF) and the electron density. Calcu-lations were carried out for H3BO3 and 27 experimentally known organoboron compounds with B-Ch bonds deposited in Cambridge Structural Database (CSD), and showed that the B-Ch bonds are covalent with similar values of basin populations (1.50-2.26e). They can be characterised as 2-center-2-electron bonds and the nature of the B-O bond differs from the B-Ch (Ch = S, Se, Te) bonds. The AIM analysis shows positive values of the Laplacian of rho(r) for BCP characterising the B-O bonding and negative values for the B-Ch (Ch = S, Se, Te) bonding. The covalency of the B-O bond may come from dative mechanism. The topological analysis of the ELF shows the B-O bond exhibits the highest median polarity of 0.82 among the studied B-Ch bonds, mainly formed by electrons from the O atom. Polarity is clearly smaller for B-Ch (Ch = S, Se, Te) bonds and its values are between 0.03 and 0.55. The covalency of the boron-chalcogen bond, predicted by calculating differences be-tween electronegativity values is anticorrelated with the basin population for the V(B,Ch) basin.

Automated summary

The local electronic structure of the boron-chalcogen B-Ch (Ch = O, S, Se, Te) bond has been investigated, revealing that the B-Ch bonds are covalent while the B-O bond differs in nature. The high polarity of the B-O bond compared to the B-Ch (Ch = S, Se, Te) bonds suggests a different electron distribution between the two types of bonds.