THE VIBRATIONAL-SPECTRA OF THE BORON HALIDES AND THEIR MOLECULAR-COMPLEXES .5. AN AB-INITIO STUDY OF THE INFRARED-SPECTRUM OF THE BORON TRIFLUORIDE-CARBON DIOXIDE COMPLEX

The optimized structures, interaction energies, Mulliken charges and v ibrational spectra of three conformers of a I:1 complex between boron trifluoride and carbon dioxide have been determined by means of ab ini tio calculations at the second-order level of Moller-Plesset perturbat ion theory, using the 6-31G basis set. All three structures feature a B ... O electron donor-acceptor interaction. One of the structures, i n which the carbon dioxide axis eclipses one of the BF bonds, was foun d to be a genuine minimum, one (the corresponding staggered form) a fi rst-order saddle point and the third (a linearly bonded B ... OCO spec ies) a second-order transition state. The computed infrared spectrum o f the preferred conformer has been used to predict the appearance of t he spectrum of boron trifluoride and carbon dioxide co-deposited in cr yogenic matrices, which will be reported in a forthcoming publication.