COMPUTATION OF THE INFRARED-SPECTRUM OF AN ACIDIC ZEOLITE PROTON INTERACTING WITH ACETONITRILE

The influence of acetonitrile adsorption on the infrared spectrum of a n acidic OH group inside a zeolite is studied by theoretical calculati ons. The zeolite is modeled by a cluster molecule. Potential energy an d dipole surfacers of the stretch and two bending coordinates of the a cidic H atom, and for the complex with acetonitrile, of an additional acetonitrile stretch coordinate, are computed employing Hartree-Fock a s well as density functional methods. Infrared frequencies as well as absorption intensities are computed taking into account mechanical as well as electric anharmonicities up to fourth order. Fermi resonance p roposed as the cause of the splitting of the OH stretch absorption ban ds in infrared spectra is explicitly considered.