Conformational preferences of the structures, and energetics of the molecular complexes of boron trifluoride with some hydrogen halides, halogens and interhalogens

The optimized structures and interaction energies of a number of complexes of boron trifluoride, as electron acceptor, with some halogen bases, as electron donors, have been determined by means of ab initio molecular orbital calculations. The bases include the hydrogen halides (HF, HCl and HBr), the halogens (F2, Cl2 and Br2), and the diatomic interhalogens (ClF, BrF and BrCl). In each case the major interaction takes place through a halogen atom of the base and the boron atom of BF3. In the complexes with the hydrogen halides the preferred conformation is the eclipsed species, while for the other two series the staggered conformer is usually more stable. The strengths of interaction correlate with some of the properties of the bases, such as the gas phase basicities, the ionization energies, the polarizabilities, and the dipole and quadrupole moments, where appropriate.