A combined experimental far-infrared and computational density functional approach applied to aluminum-alkyl cocatalysts

The structure of aluminiummethyl(chloride) complexes is investigated by experimental far-infrared spectroscopy and by density functional theory calculations. The vibrational frequencies and relative intensities are reproduced well using the B3-LYP based density functional method (DFT). The computed spectra allow for a unique identification of the configuration of the aluminiummethyl(chloride) complexes. The results show that far-IR spectra may be accurately predicted for medium-sized molecules using DFT calculations with moderate basis sets size.