Accuracy of Computed N-15 Nuclear Magnetic Resonance Chemical Shifts

作者：Gregusova Adriana; Perera S Ajith; Bartlett Rodney J^*

来源：Journal of Chemical Theory and Computation, 2010, 6(4): 1228-1239.

DOI：10.1021/ct9005739

Benchmark CCSD(T) N-15 NMR calculations are performed for 35 experimentally known N-15 shifts of 29 molecules. For the eight known gas phase experimental values of N-2, HCN, CH3CN, N (N) under barO, NH3, (N) under bar NO, (CH3)(3)N, and CH3NH2, CCSD(T) with a basis set previously calibrated for C-13 shifts is accurate to 0.2-3 ppm except for the (N) under bar NO shift, which shows a deviation of 6 ppm. However, the differences between the compute and experimental values in solution due to solvent and finite temperature effects can be as large as similar to 25 ppm and must be estimated to relate gas phase 0 K computed values to experiment. An empirical correction is obtained by studying the variations between the estimated solvent effects and the absolute shielding constant. It is shown that the average deviation of computed shifts falls to 3.6 ppm from 12.6 ppm when the correction is applied.

• 出版日期2010-4