The vibrational spectra of the boron halides and their molecular complexes. Part 13. Ab initio studies of the complexes of boron trifluoride with formaldehyde and some of its analogs

Abstract

ABSTRACT:The structure, the interaction energy, and the vibrational spectrum of the electron donor-acceptor complex formed between boron trifluoride, as a Lewis acid, and formaldehyde, as a Lewis base, have been determined by means of ab initio calculations at the second-order level of Møller-Plesset perturbation theory, using a triple-zeta basis set with polarization and diffuse functions on all atoms. The object was to examine the differences in the properties of the complexes formed between boron trifluoride and an oxygen base containing oxygen in the sp 2 hybrid state with those of some sp 3 oxygen bases studied earlier. The investigation has then been extended to include the related bases thioformaldehyde and methanimine, to assess the effect of substituting the oxygen atom by a sulphur atom or an imino group. A further range of formaldehyde analogs, containing one and two methyl groups, one and two fluorine atoms, and one methyl group and one fluorine atom, has also been included. The preferred structure of each complex has been identified. The computed data have been compared, and the complex properties correlated with some relevant physical properties of the bases.

Theoretical Study of the Regioselectivity of the Interaction of 3-Methyl-4-pyrimidone and 1-Methyl-2-pyrimidone with Lewis Acids

“…The NBO interaction energy is three times larger than the corresponding formaldehyde boron overlap interaction energy. The whole of these results is in line with earlier stabilization energy calculations by Ford et al on complexes between BF 3 and small oxygen and nitrogen bases . The amount of charge transfer for this N–B donor–acceptor interaction is twice as large as the oxygen boron charge transfer (Tables and ).…”