The vibrational spectra of the boron halides and their molecular complexes. Part 4. Ab initio predictions of the structures and vibrational spectra of the complexes of boron trifluoride with dimethyl ether and dimethyl sulphide

摘要

The optimized structures and vibratkmal spcclru of the 1:1 complexes of boron Irifluoride with dimethyl ether and dimethyl sulphide have been determined by means of u scries of ub inilio calculations using the (5/vussian-o.o computer program at the tac-Fock level with the fi H1 Ci basis set. 'rite results have been rationalized on the basis of the interactions of the Lewis acid (BF_3) with a hard ((CH_3)_2O) Hittl a Mill base. The magnitudes of the wnvcnumber shifts, both for (he acid and the tec fragments, arc far larger tor the complex with tlte hard than with the soft base. The computed results have been used as aids Inilic interpretation of the infrared spectra of BF_3 co-condensed with (CH_3)_2O and with (CH_3)_2S in cryogenic matrices, to be [tpoticd in a forthcoming publication.