The Binary Boron Trifluoride-Hydroxylamine Molecular Complex: N-Bound or O-Bound?

Boron trifluoride acts as a classical Lewis acid in forming molecular complexes with a variety of electron donors. Recent computational results on a number of complexes with some oxygen and nitrogen bases have indicated relationships between the properties of the adducts, such as the interaction energies and the wavenumber shifts of some of the modes of the boron trifluoride sub-molecule, and some physical properties of the bases. Hydroxylamine represents an example of a base containing two potential sites of electron donation, the nitrogen and the oxygen atoms. Predictions based on our earlier investigations of systems of this type suggest that hydroxylamine would bind to boron trifluoride preferentially through its nitrogen atom. Whether such a complex adopts an equilibrium structure in which the NO bond of hydroxylamine lies cis or trans to one of the BF bonds of boron trifluoride is more difficult to predict. This paper investigates the relative binding properties of N-bound versus O-bound complexes of boron trifluoride with hydroxylamine, and explores the conformational preferences and vibrational spectra of both types of adduct.Keywords: Ab initio calculations, molecular complexes, boron trifluoride, hydroxylamin