Normal coordinates analyses of beta-D-allose and alpha-D-talose in the crystalline state

IR and Raman spectra of beta-d-allose, alpha-d-talose and beta-d-allose O-D(5) have been recorded in the 4000-400 cm(-1) and in the 4000-20 cm(-1) regions. These spectra constitute the experimental support that allows to reproduce theoretically the vibrational frequencies and to establish a force field for these saccharides through a normal coordinate analysis. For this purpose, a modified UBSFF has been combined with an intermolecular potential energy function that includes the Van der Walls interactions, the electrostatic terms, and an explicit hydrogen bond function. The initial force field parameters are derived either from those of D-glucose or D-galactose and are fitted so as to obtain a good agreement between the calculated and the observed frequencies. The obtained results reproduce the experimental frequencies and in order to test the validity of the obtained force field, it has been applied to beta-D-allose O-D(5).