Poulter, CD
1994
The N-15 Chemical Shift Tensors of Uracil Determined from N-15 Powder Pattern and N-15/C-13 Dipolar NMR Spectroscopy
Anderson-Altmann, K.L.; Phung, C.G.; Mavromoustakos, S.; Zheng, Z.; Facelli, J.C.; Poulter, C.D. and Grant, D.M.
Journal of Physical Chemistry, 1994 (in press). Funded by National Science Foundation.
The N-15 chemical shift tensors of uracil are detemined by N-15 powder pattern techniques. The principal values of the N-15 uracil tensors are obtained from the spectra of [1-N-15]uracil and [3N-15]uracil, and the tensor orientations are determined from the spectrum of [1,3-N-152, 2-C-13]uracil with the inclusion of dipolar interactions. Ambiguities in the orientational assignments are resolved using molecular symmetry considerations and results of ab initio calculations of the N-15 chemical shielding tensors. The N1 nitrogen has principal values of 196 ppm, 114 ppm, and 30 ppm and the N3 nitrogen 200 ppm, 131 ppm, and 79 ppm with respect to N-15H4NO3. The components with the largest chemical shifts lie approximately along the N-H bonds. Including the effect of intermolecular hydrogen bonds on the theoretical calculations improves in a significant way the agreement between the calculated and experimental chemical.
Poulter, CD
1994
The N-15 Chemical Shift Tensors of Uracil Determined from N-15 Powder Pattern and N-15/C-13 Dipolar NMR Spectroscopy
Anderson-Altmann, K.L.; Phung, C.G.; Mavromoustakos, S.; Zheng, Z.; Facelli, J.C.; Poulter, C.D. and Grant, D.M.
Journal of Physical Chemistry, 1994 (in press). Funded by National Science Foundation.
The N-15 chemical shift tensors of uracil are detemined by N-15 powder pattern techniques. The principal values of the N-15 uracil tensors are obtained from the spectra of [1-N-15]uracil and [3N-15]uracil, and the tensor orientations are determined from the spectrum of [1,3-N-152, 2-C-13]uracil with the inclusion of dipolar interactions. Ambiguities in the orientational assignments are resolved using molecular symmetry considerations and results of ab initio calculations of the N-15 chemical shielding tensors. The N1 nitrogen has principal values of 196 ppm, 114 ppm, and 30 ppm and the N3 nitrogen 200 ppm, 131 ppm, and 79 ppm with respect to N-15H4NO3. The components with the largest chemical shifts lie approximately along the N-H bonds. Including the effect of intermolecular hydrogen bonds on the theoretical calculations improves in a significant way the agreement between the calculated and experimental chemical.