C-13 high-resolution solid state NMR studies of the structure and dynamicsof 1,6 : 3,4-dianhydro-2-O-tosyl-beta-D-galactopyranose

C-13 CP/MAS, dipolar dephasing MAS and theoretical GIAO calculations were e mployed to assign C-13 resonances to the molecular structure of 1,6:3,4-dia nhydro-2-O-tosyl-beta-D-galactopyranose 1. From spinning sideband intensiti es, employing the graphical method of Herzfeld and Berger the C-13 delta(ii ) parameters for aromatic residue were calculated. The experimental data we re compared with computed results obtained by means of the B3PW91 hybrid me thod and 6-311G (df, p) basis set. The X-ray geometry of 1 with the correla ted position of hydrogen atoms was taken as input data for theoretical calc ulations. As concluded from Cambridge Crystallographic Database (CSD) searc h, there are two reports describing the X-ray studies of 1 that show the sl ightly different geometry of the compound under investigation. This work sh ows that such discrepancies in geometry can generate differences between co mputed C-13 delta(ii) parameters up to 6 ppm. C-13 T-1 and H-1 T-1p relaxat ion times reveal that 1 is very rigid in crystal lattice. This structure is characterized by extremely long H-1 T-1p, found to be in range ca. 200 ms. (C) 2000 Elsevier Science B.V. All rights reserved.