Vibrational spectra of CO2-electron donor -: Acceptor complexes from ab initio

In this paper,. we investigated the 1: 1 EDA complexes Of CO2 formed with alcohols, namely, methanol and ethanol (Sp(3) O-donating atom), and with acetone (Sp(2) O-donating atom) in light of ab initio calculations. The interaction energy and the geometry of the complexes have been evaluated with the Moller-Plesset perturbation theory at the second-order level (MP2) using Dunning's basis sets. The predicted structures are found to be rather similar compared with the calculations at the SCF/3-21G* level reported by Jamroz et al. (Jamroz, A H.; Dobrowolski, J. C.; BaJdor, K.; Borowiak, M. A. J. Mol. Struct. 1995049, 9.). Nevertheless, the stabilization energies are found in our work to be 2 to 2.5 times lower including electron correlation. In addition, we have analyzed the vibrational spectra of these EDA complexes. In particular, we emphasized the splitting of the V-2 bending mode Of CO2 and the vs(OH) stretching mode of alcohols or the antisymmetric nu(a)(CCC) and symmetric v(s)(CO) stretching modes of acetone. Finally, the shift and the IR and Raman intensity variations under the complex' formation are discussed and compared with infrared absorption and Raman experimental measurements.