A THEORETICAL-STUDY OF VIBRATIONAL-SPECTRA OF TETRANITRATE-METHYL-BETA-D-GLUCOPYRANOSIDE AND 2,3-DI-O-NITRO-METHYL-BETA-D-GLUCOPYRANOSIDE

Coupled calculations were carried out of normal vibration frequencies from the point of view of the valence-force field scheme and of absolu te IR band intensities by the CNDO/2 method for the tetranitrate-methy l-beta-D-glucopyranoside molecule. A good agreement was achieved with the experiments. Normal coordinate analysis was made for 2,3-di-O-nitr o-methyl-beta-D-glucopyranoside molecule with force constants obtained for the tetra-nitrate-methyl-beta-D-glucopyranoside. Before proceedin g to the calculation of the spectra of such complex molecules of nitra tes of monosaccharides, a complete experimental and theoretical invest igation was performed of the vibrational spectra of methylnitrate, whi ch made it possible to determine the deficit of force constants for th e calculations of the spectra of nitrosubstituted glucopyranosides. De tailed interpretations of the observable IR spectra of both the nitro- glucopyranosides compounds considered are given. The absorption spectr a sensitivity to the spot of the nitrate group localization was discov ered. Special attention was focused on analyzing the spectra of nitrat es of saccharides for the characteristic split of the band due to the asymmetric stretching vibrations of the ONO2 groups in the region of 1 700-1600 cm(-1). (C) 1998 Elsevier Science B.V.