Validation of a computational scheme to study 15N and 13C nuclear shielding constants

The performance of the DFT functionals B3LYP, B3PW91 and PBE1PBE in conjunction with selected basis sets for the prediction of N-15 and C-13 nuclear shieldings for small nitrogen-containing molecules is assessed. For molecules containing only singly bonded nitrogen and carbon atoms, the PBE1PBE/6-311+G(2df,p) level of theory is shown to provide reliable N-15 and C-13 nuclear shieldings. For the triply bonded nitrogen-containing molecules N-2, CH3CN and HCN, all three levels of theory are much less satisfactory. (C) 2004 Elsevier B.V. All rights reserved.