Insight and performance of LC‐DFT vs DFT in the NMR shielding and chemical shift calculations: Case of CHClCHCF3

Abstract

AbstractFifteen density functional theory (DFT) methods and fifteen long‐range corrected density functional theory (LC‐DFT) methods were used in the present work to assess nuclear magnetic resonance parameters such as nuclear shielding constant (NSC), nuclear chemical shift (NCS), and nuclear anisotropic shielding constant (NAS). These different methods were associated with the full basis set 6‐311++G(3df,3pd). The gauge‐independent atomic orbital was used for the calculation of nuclear shielding tensors of the nuclei contained in the stereoisomers cis‐ and trans‐CHClCHCF3. Thus, the effects of LC are clearly observed for heavy nuclei (13C, 19F, 35Cl). The results of NSC, NCS, and NAS from DFT are better described than LC‐DFT with regard to the KT3 method. Moreover, the results from the LC‐DFT are better described than the standard DFT with regard to CCSD(T). Based on the latter method used as the benchmark, the NSCs of nuclei are well fitted by the competitive functionals LC‐TPSSTPSS and LC‐PKZBPKZB. In the particular case of the trans‐isomer, mPWPKZB was found to be the best method. For the NCSs, the more accurate methods include the latter two LC functionals and the non‐LC functionals TPSSTPSS and mPWPKZB. The accuracy of NAS depends strongly on the nuclei. Thus, CAM‐B3LYP describes it well for 19F and LC‐PKZBPKZB for 35Cl. The rest of nuclei are well fitted by all the methods except 13C1 and 13C2, which are better reproduced by the LC‐DFT except the LC‐PKZBPKZB, LC‐TPSSTPSS, and CAM‐B3LYP functionals.