Abstract
The structure, the interaction energy, and the vibrational spectrum of the electron donorβacceptor 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 secondβorder level of MΓΈllerβPlesset perturbation theory, using a tripleβzeta 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. Β© 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012