The aim of this study is to investigate the possible cooperative effects between B•••N and hydrogen- or lithium-bonding interactions in the ternary H3B···NCM···Z, F3B···NCM···Z and C5H5B···NCM···Z complexes, where M=H, Li and Z= NH3, N2. The characteristic of the interactions in these complexes is studied by molecular electrostatic potential, quantum theory of atoms in molecules and natural bond orbital analyses. For all these complexes, the M•••N binding distances are always shorter than those in NCM···Z binary complexes, which implies that the formation of the B•••N interaction strengthens the M···N bonds. However, unlike H3B···NCM···Z and F3B···NCM···Z complexes, the B···N binding distances in C5H5B···NCM···Z are found to be longer than those in C5H5B···NCM dimers. Such unusual cooperativity between the B···N and hydrogen- or lithium-bonding interactions has not been reported previously. The origin of this unusual cooperativity between B···N and M···N interactions in C5H5B···NCM···Z complexes is explained in term of the back-bonding π→π* charge-transfer between C5H5B and NCM moieties.
