Theory of Electronic Structure and Nuclear Quadrupole Interactions in the BF3-NH3 Complex

Boron Trifluoride is widely used as a catalyst in chemical research and industry forming complexes in the process with other molecules like NH$_{3}$, H$_{2}$O, and CH$_{3}$OH. We have studied the BF$_{3}$-NH$_{3}$ molecular complex using Hartree-Fock procedure combined with many-body perturbation theory. The B-N bond is found to involve about 75{\%} covalent and 25{\%} van der Waals characters. The calculated geometry of the complex compares well with experimental results. The nuclear quadrupole interaction parameters for the $^{19}$F* nucleus [1] show good agreement with experiment for both solid BF$_{3}$ and the complex including the nuclear quadrupole coupling constants and the sizable asymmetry parameters. The $^{11}$B quadrupole coupling constant is however found to be about 1.5 times the available experimental value [2] for solid BF$_{3}$, possibly due to the influence of intermolecular bonding. \newline \newline [1] K. Bertholdt et al. J. Mol. Struct. 192, 199 (1989) \newline [2] P.A. Casabella and T. Oja J. Chem. Phys. 50, 4814 (1969)