The vibrational spectra of the boron halides and their molecular complexes .3. Ab initio predictions of the structures, energetics, and Mulliken atomic charges of the complexes of boron trifluoride with some linear nitrogen donors

The structures of the 1:1 electron donor-acceptor complexes of boron trifluoride with a number of linear nitrogen bases (N-2, N2O, HCN, FCN, C2N2, and HCCCN) have been optimized by means of a series of ab initio molecular orbital calculations, performed at the second order level of Moller-Plesset perturbation theory with the 6-31G** split-valence polarized basis set. The interaction energies have been computed and corrected for basis set superposition error and for zero-point energy difference. The Mulliken atomic charges of each atom have also been determined, and the changes on going from monomer to complex have been noted. The structural results are discussed in terms of the perturbation of the monomer properties (BF bond length and distortion from planarity) and the establishment of new complex properties (B...N bond length and FBN bond angle) on complexation. The structural changes and shifts of electronic charge, and the interaction energies, are correlated with the strengths of the interactions, estimated by the experimentally determined proton affinities and the absolute electronegativities of the nitrogen donors.