Computational NMR coupling constants: Shifting and scaling factors for evaluating 1 J CH

• Published in: Magnetic resonance in chemistry 2013-12, Vol.51 (12), p.775-787
• Main Authors: San Fabián, J., García de la Vega, J.M., Suardíaz, R., Fernández‐Oliva, M., Pérez, C., Crespo‐Otero, R., Contreras, R.H.
• Format: Article
• Language: English
• ISSN: 0749-1581; 1097-458X
• DOI: 10.1002/mrc.4014

Optimized shifting and/or scaling factors for calculating one‐bond carbon–hydrogen spin–spin coupling constants have been determined for 35 combinations of representative functionals (PBE, B3LYP, B3P86, B97‐2 and M06‐L) and basis sets (TZVP, HIII‐su3, EPR‐III, aug‐cc‐pVTZ‐J, ccJ‐pVDZ, ccJ‐pVTZ, ccJ‐pVQZ, pcJ‐2 and pcJ‐3) using 68 organic molecular systems with 88 1 J CH couplings including different types of hybridized carbon atoms. Density functional theory assessment for the determination of 1 J CH coupling constants is examined, comparing the computed and experimental values. The use of shifting constants for obtaining the calculated coupling improves substantially the results, and most models become qualitatively similar. Thus, for the whole set of couplings and for all approaches excluding those using the M06 functional, the root‐mean‐square deviations lie between 4.7 and 16.4 Hz and are reduced to 4–6.5 Hz when shifting constants are considered. Alternatively, when a specific rovibrational contribution of 5 Hz is subtracted from the experimental values, good results are obtained with PBE, B3P86 and B97‐2 functionals in combination with HIII‐su3, aug‐cc‐pVTZ‐J and pcJ‐2 basis sets. Copyright © 2013 John Wiley & Sons, Ltd.