On the multiple B-N bonding in boron compounds using the topological analysis of electron localization function (ELF)

Topological analysis of the Electron Localization Function (ELF) within the framework of Quantum Chemical Topology (QCT) has been applied to study the nature of the boron-nitrogen bonds. A series of 10 compounds have been chosen, with the B-N bond length ranging between 1.698 angstrom (B-N) and 1.258 angstrom (B=N). According to the Lewis formula three types of bonds have been recognized. These are: the single B-N bond with a basin population of 1.91 divided by 2.09e, the double B-N bond with a population of 3.78 divided by 4.28e, and the triple B N bond with a basin population of 5.72 divided by 5.74e. In the case of partial double bonds (B - N), where formally two or more resonance hybrids have to be considered, our calculations strongly support the concept of double boron-nitrogen bonding (B=N).