Unveiling the Features of Bonding in Penta-Coordinated Carbon and Boron Derivatives from Orbital and Electron Density...

The electronic criterion and the recently suggested two-factor descriptor based on orbital-free density functional theory are analyzed for distinguishing different types of O-B/O···B and O-C/O···C bonding in 9-anthracenyl derivatives. These descriptors are based on the comparison of the distances of extreme positions of the electrostatic and total static potentials along the bond line. Nonclassical cases of bonding, including sterically hindered derivatives of penta-coordinated carbon and boron atoms, have also been considered using NBO analysis. It was demonstrated that both techniques provide complementary conclusions about the bonding type in the considered structures. They allow distinguishing covalent and noncovalent bonds, as well as recognizing the formation of weak O···C⁺···O bonds.