Impacts of basis sets, solvent models, and NMR methods on the accuracy of 1H and 13C chemical shift calculations for biaryls: a DFT study

Abstract

Introduction: Biaryls are core structures composed of chiral ligands, organocatalysts, biologically active natural products and biopolymer lignins. In this study, the effects of basis sets, solvent models, and NMR methods on the accuracy of 1H/13C NMR chemical shift calculations for biaryl structures were evaluated. Methods: All calculations were performed using Gaussian09. The GIAO NMR results were observed and extracted using GaussView05. To reduce the systematic error of the calculations, linear regression analysis of the calculated chemical shifts versus the experimental shifts was performed. Results: The tested basis sets showed good 1H/13C results, with CMAE values as low as 0.0425 ppm and 1.09 ppm for 1H and 13C, respectively. The use of solvent models significantly increased the accuracy of the 1H chemical shift calculations. The GIAO method produced more accurate results than did the IGAIM and CSGT methods. Conclusion: This study recommends 6-31G(d,p) and DGDZVP basis sets, IEMPCM and CPCM solvent models, and GIAO NMR methods for the accurate prediction of 1H and 13C chemical shifts for biaryls, assisting in their full structural assignments.