Bonding analysis in b-diketiminate boron and related systems has been performed. For the optimized geometries (MP2/aug-cc-pVTZ), the post-SCF electron density function has been produced and its topological parameters have been analyzed according to Atoms in Molecules Quantum Theory approach. The B-N bond has characteristics similar to those found for TM-ligand bonding. The symmetric character of the B-N interaction found for the b-diketiminate boron results from the fully p-electron delocalized character of the b-diketiminate moiety. If the p-electron system in NCCCN sequence of bonds is localized, the asymmetric B-N bonding is enforced.