NONEMPIRICAL QUANTUM-CHEMICAL CALCULATION OF THE SHIFT OF THE UPSILON(CN) FREQUENCY OF ACETONITRILE IN THE CASE OF COORDINATION WITH LEWIS ACID CENTERS

An ab initio calculation of the structure and force constants of aceto nitrile and its complexes with Lewis acids AlCl3, AlF3, and Al(OH)3 ha s been performed. Scaling factors permitting reproduction of the exper imental spectrum of the complex CH3CN-AlCl3 have been found. Scaled vi brational spectra of the complexes CH3CN-AlF3, and CH3CN-Al(OH)3 were calculated; the latter was examined as the simplest molecule of the co ordination of acetonitrile on a Lewis acid center of aluminosilicates. A comparison of the calculated spectrum of the complex CD3CN-Al(OH)3 with the experimental spectrum for the adsorption complex of deuteroac etonitrile on zeolite HZSM-5 suggested that deuteroacetonitrile is coo rdinated on the Al atom of the Lewis acid center.