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On the accuracy of the GIAO‐DFT calculation of 15 N NMR chemical shifts of the nitrogen‐containing heterocycles – a gateway to better agreement with experiment at lower computational cost
Author(s) -
Samultsev Dmitry O.,
Semenov Valentin A.,
Krivdin Leonid B.
Publication year - 2014
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.4055
Subject(s) - chemical shift , chemistry , basis set , density functional theory , carbon 13 nmr , computational chemistry , basis (linear algebra) , series (stratigraphy) , mathematics , stereochemistry , paleontology , biology , geometry
The main factors affecting the accuracy and computational cost of the gauge‐independent atomic orbital density functional theory (GIAO‐DFT) calculation of 15 N NMR chemical shifts in the representative series of key nitrogen‐containing heterocycles – azoles and azines – have been systematically analyzed. In the calculation of 15 N NMR chemical shifts, the best result has been achieved with the KT3 functional used in combination with Jensen's pcS‐3 basis set (GIAO‐DFT‐KT3/pcS‐3) resulting in the value of mean absolute error as small as 5 ppm for a range exceeding 270 ppm in a benchmark series of 23 compounds with an overall number of 41 different 15 N NMR chemical shifts. Another essential finding is that basically, the application of the locally dense basis set approach is justified in the calculation of 15 N NMR chemical shifts within the 3–4 ppm error that results in a dramatic decrease in computational cost. Based on the present data, we recommend GIAO‐DFT‐KT3/pcS‐3//pc‐2 as one of the most effective locally dense basis set schemes for the calculation of 15 N NMR chemical shifts. Copyright © 2014 John Wiley & Sons, Ltd.