An ab initio molecular orbital study of the complexes formed between silicon tetrafluoride and some Lewis bases

The structures, interaction energies and vibrational spectra of the electron donor-acceptor complexes formed between silicon tetrafluoride and the common Lewis bases ammonia, water, phosphine and hydrogen sulphide have been determined by means of a series of ab initio molecular orbital calculations. The results confirm the trends observed in our previous studies of the complexes formed between the same four bases and the Lewis acids boron trifluoride and sulphur dioxide. The analogous complexes of silicon tetrafluoride with hydrogen fluoride and hydrogen chloride were also examined and, consistent with our earlier findings concerning the adducts of boron trifluoride and sulphur dioxide with these two diatomic species, were found to be very weakly-bound, if at all.