The vibrational spectra of the boron halides and their molecular complexes, part 5An ab initio study of the infrared spectrum of the boron trifluoride-carbon dioxide complex

The optimized structures, interaction energies, Mulliken charges and vibrational spectra of three conformers of a 1:1 complex between boron trifluoride and carbon dioxide have been determined by means of ab initio calculations at the second-order level of M?ller-Plesset perturbation theory, using the 6-31G* basis set. All three structures feature a B⋯O electron donor-acceptor interaction. One of the structures, in which the carbon dioxide axis eclipses one of the BF bonds, was found to be a genuine minimum, one (the corresponding staggered form) a first-order saddle point and the third (a linearly bonded B⋯OCO species) a second-order transition state. The computed infrared spectrum of the preferred conformer has been used to predict the appearance of the spectrum of boron trifluoride and carbon dioxide co-deposited in cryogenic matrices, which will be reported in a forthcoming publication. Received: 18 November 1996 / Accepted: 11 March 1997